Thanks for actually explaining it, instead of doing what everyone else does and saying "It's because you're in freefall!" without giving any explanation whatsoever.
in the case of something orbiting, the acceleration is perpendicular to the velocity. This means it can change the direction of velocity but not its magnitude. For acceleration to cause a change in speed it must have a component in the same (or opposite) direction to velocity.
As my physics lecturer would say "You are never weightless, you are however, normalforceless. It is this normalforcelessness that you call weightless. You cannot perceive weight"
2) One important thing to consider is that the force of gravity cannot really be felt. The only reason we have a sense of weight is because for the most part, we are all experiencing forces that COUNTER the force of gravity. So when you stand on the ground, you are not feeling the force of gravity, you are feeling the force of the ground pushing you up (usually with an equal and opposite force of gravity). When in free fall, there are no countering forces, so you FEEL weightless. but you're not.
Such a simple concept, but did not know until I was about 50. Am 70 now. Why in the !&#* didn't one of my teachers back in the 1960s' spend just 3 minutes explaining. And this was when orbiting the earth was BIG news. Thank you Veritasium for filling some of the huge gaps.
planes don't go fast enough to "orbit". You are a little lighter 1) because you are 10km further from Earth's surface and 2) because some of your weight force is used to accelerate you in circular motion as you pass over Earth's surface.
If you are on your way to the moon, you really do reach a point where the Earth's gravity is negligible. Two Earth diameters away from Earth and your weight would be 4% of its present value (and the moon is roughly 30 Earth diameters away)
@@damprotek Gravity is not something you feel directly. You feel gravity through a force that resists it, like an elevator, a rocket, a floor in a building, an airplane (that isn't falling), or the ground of the earth itself. Every time the ISS "reboosts" itself to correct its orbit, the astronauts feel some resistance, and hence don't feel completely weightless at that moment in time.
no, a plane and a space station have very different orbits. Planes fly at 10 km, much lower than 300km and they fly through much thicker atmosphere, making faster flying (>27000 km/h) impossible. But yes if they could go fast enough they would orbit, with weightless passengers inside.
So, would I feel the exact same sensation here on earth if I were to, say, jump off of a building while inside some type of container? The "container" is just there so I don't feel the air resistance.
yeah actually, until the container hits terminal velocity it would effectively fall at the same speed as you so relative to the container you'd be weightless.
+KingHalbatorix Not exactly. You'd need to jump off a building in a vacuum; box or not. Being inside the box doesn't eliminate drag. The drag is just on the box now, and it would NOT be in free fall in air. It doesn't accelerate at 9.8 m/s² and then all of a sudden stop accelerating at terminal velocity; the acceleration would gradually decrease as the drag force increased until it reached zero - at which point you would feel like you were just sitting on a box on the ground. What would actually happen is you would feel weightless at first (for a split second) and you would feel heavier and heavier until you reached terminal velocity and then you'd feel as heavy as you do on the ground.
Just go to a theme park and get on some of the rides! That's what it should feel like all the time. Then think about it and question if you believe they are actually out there. The orbits they use are .9G free fall , NOT 0G.
well the space station is not that much further as a proportion of orbital radius, plus the velocity is inversely proportional to the square root of r so I think the similarity makes sense.
Hey, i really like ur videos, u make things easy to understand, can you post a video about cellular systems, no other video can be as helpful as yours!!
Interesting question. I don't know the answer either but is the answer somewhat similar to why the Earth's rotation around the sun and the moon's rotation around the earth are not speeding-up?
There may be a distance at which our best intruments could no longer detect the gravitational pull of earth, but technically the pull of gravity extends to infinity with the force decreasing proportional to the square of the distance.
Hi, Recently I saw the movie Gravity, I really liked it but something is really bothering me about the movie. There is a scene where the satellite debris hit the Hubble Space Telescope and the astronaut gets loose in space, in this case, because of the gravitational forces, whouldn't the astronaut start falling into earth? This Really Bothers Me So I Will Be Very Thankful If You Could Answer Me.
The ISS goes around the world in 90 minutes, so does the astronaut - they have a speed of 25,000 miles per hour. If the astronaut jumps off at 10 mph, she is still traveling at 25,010 mph, so she goes around the world. 90 minutes later she is only 15 miles in front of the space station and will travel like that for a year or more until air friction slows her down enough to fall to thicker air where she will burn up as a meteor.
That's why railguns putting things into orbit on Earth isn't a good idea. "How much of the atmosphere would you like to put the payload through?" Railgun- Yes
Great video. One thing that was not explained is that the space station's sideways velocity is able to prevent it from falling to Earth due to there being very little resistance from the atmosphere. If the space station were much closer to Earth, it would slow down due to atmospheric resistance and fall to Earth. It is both the sideways velocity and the lack of resistance that prevents the space station from falling to Earth.
Just out of curiosity, I calculated the orbital velocity at 10km from earth, and got 7900 m/s or 28440 km/h or 7.9 km/s. I found it surprising how close that is to the ISS's speed at 7706.6 m/s (also 27744 km/h or 7.71 km/s)
Velocity is a vector quantity with a magnitude (speed) and a direction. A change in direction is just as much an acceleration as a change in speed is, and objects in orbit are constantly changing direction. You could also call this centripetal acceleration and it is consistent with universal gravitation. For example, the acceleration of a falling body at the surface of the Earth is 9.8 m/s^2. A hypothetical object in orbit right at the surface has the same acceleration.
stopped at 1:31 .. the space station is actually free-falling... so when astronauts are floating... they are actually free falling like sky diving.. I don't know if the exact terms as to why.. but I know its free falling... let's see if I was right.
I thought the centrifugal force of orbiting neutralizes the gravitational force. it's half right, the actual phenomenon is the same but seen at a different perspective.
nextlifeonearth Nope. You've actually mixed up the different frames of reference yourself. If gravity were treated as a force that shows up in one frame of reference, then the corresponding centrifugal force only shows up in the rotating frame of reference. The two NEVER shows up in the same frame of reference and "cancel out". This is how, for example, spinning a bucket of water won't end up having water everywhere - you apply the centripetal force in your frame of reference. In the rotating frame of reference of the water, there is no centripetal force - only centrifugal force. Think about it - by your faulty analysis, if the two cancels out, the water in the bucket is weightless - it wouldn't stay in the bucket at all (and you wouldn't feel the weight of the bucket)! All this is moot anyways, because gravity isn't really a force. All orbits are inertial paths, meaning there are no forces acting on you.
Narcissist86 you're either an idiot or really bad informed, no offence. The gravitational force of the earth would be the arm holding the bucket(satellite) and this is present, believe me. If you turn a bucket slower the water would be weightless in the bucket. (even slower and it'll get wet al over) if the satellite goes faster it'll move away from the earth(more outward centrifugal force, more acceleration, moving away) should he go slower, it'll fall to earth.
nextlifeonearth Sorry, ad hominem attacks don't work, especially when it's clear you don't know what you're talking about. I'm going to guess you have only about high school education on the matter, so it's really ironic when you call someone an idiot when there is such a large knowledge gap. But you know, you need to have SOME knowledge to know the limits of that knowledge. As I said before, in general relativity orbits are geodesics - inertial paths through space. There are no proper forces whatsoever. So there is no need to get bogged down on wrong-minded discussions on centrifugal forces. "If you turn a bucket slower the water would be weightless in the bucket." Wrong. Please read up on centrifugal forces, and how it never appears in the same frame of reference as centripetal force. They never appear in the same frame to "cancel out". It's almost like you've never done free body diagrams in rotating reference frame before!
Narcissist86 calling it weightless might have been wrong, I meant relative to the bucket it would appear weightless and because of the centrifugal force it does not drop down, I asked a professor in physics if you were right, he said you were kinda right but so was I so don't try to disregard different views for the same thing. You might have understood me wrong and I apologise for calling you an idiot, but I don't like being called wrong when there are no real arguments opposing my theories.
so its falling towards the earth but because they are falling so fast it falls away from the earth and the gravitational pull keeps it at the same distant away from the earth,
And like I said in my very first post explaining this, it is not velocity and gravity that are in balance like you said. It is the inertia/momentum and gravity that are in balance.
food are not floating since there is low amount of space in the stomach, its pretty tight in there. It just expand on the amount of food that get in. yeah it affect digestion since the effect of the lack of gravity actually make foods moving very very slower through the body. They don't shower, they use a special kind of soap that don't need water. if i remember right, its some kind of gel. Water is vital up there, and cost a lot to carry. so they drink it instead
Really awosome video!! Just perfect. I loved you practising the concept of science-teaching video and bringing it solidly into reality. That was a perfect ,complete scene showing the whole theoritical concept.(Y) APPRICIATE!!
What Ciaran said is right. I'd just like to add this. It's surface tension will pull the molecules together and form the most efficient shape, and a sphere has the least amount of surface area for a given volume, so a sphere is the most efficient shape.
TONY BUI g is accelerarion, bud. G-force is a unit of apparent acceleration. 1 G-force is an apparent acceleration of 9.8 m/s^2. When standing on the surface of the Earth, your are experiencing 1 G-force. It's not a force. It's the apparent acceleration felt. When in free fall, you experience zero G-forces. You feel zero apparent accelerations. This is what "zero g" and "zero gravity" mean. This is simple fact. You people don't have to accept this, but you're wrong if you dont. It's really of no consequence to me either way.
+Willoughby Krenzteinburg g is not force. g is gravitational field strength or to put it in other words, force per unit mass or to put it in even simpler words, acceleration due to gravity. If a body is experiencing a force of 1g, it means that the body is accelerating at a rate of 9.81 m/s2.
Actually, while it might come off that way, he has done studies that show people learn more via video when it is presented in the way he does here (presenting the misconceptions people have to begin with, then correcting them). His name is Derek Muller. Read up on him. It's actually quite interesting. His thesis was on this. I think it is titled "Designing Effective Multimedia for Physics Education". In other words, he has done his homework and is helping people. He deserves props.
Acceleration is any change in speed or direction of movement. So think of the spacestation as constantly falling towards Earth and just missing the ground. It keeps changing its direction because when it gets to the other side of the Earth, it's now being pulled a different direction. That means it has "accelerated" because it's being pulled in a different direction.
Acceleration is a change in velocity. Velocity is a vector quantity, which means it has both speed and a direction. Objects in orbit are constantly changing direction (since they are orbiting in a circular trajectory), therefore they are accelerating. A change in direction is just as much an acceleration as a change in speed is.
They are constantly accelerating toward the center of Earth. That is the force vector, so the acceleration vector points toward the center of Earth as well. The important thing to understand is that acceleration is a vector quantity, which means it has a magnitute (velocity) and a direction. This means that a change in direction is just as much an acceleration as a change in velocity is. At any given instant, the ISS is accelerating (changing direction) toward the center of Earth.
this is alot better than other videos ive seen i kinda stopped watching because he would spent 5 mins asking people questions and getting wrong answers then finally after 5 mins get the answer. but this is good pace few answers and then he answers it
You should try to get these episodes on some science channel, they are brilliant and really teaches fun stuff that regular people can enjoy and apprieciate!
Acceleration is also a vector quantity, with a magnitude and direction as well. Objects in orbit are constantly accelerating (changing direction), and the acceleration vector is pointed toward the center of the Earth. This is why you say that objects in orbit are constantly accelerating toward the center of the Earth.
To answer your question, if you were to drop a rock from an elevation equal to where the ISS orbits, the acceleration of the rock, and the acceleration of the ISS would be identical. It's just that the rock accelerates in a linear fashion (acceleration only affects speed), and the ISS is accelerating angularly (centripetal acceleration), but the accerations are the same. If you ignored air resistance, and put something in orbit near the surface, its centripetal acceleration would be 9.8m/s².
The first cosminc speed would be the velocity required to orbit the Earth right at the surface. It obviously ignores any drag. The second cosmic speed is the escape velocity of the Earth, and the third cosmic speed is the escape velocity of the sun.
@everyday420ful. They are accelerating at a constant rate, but their speed is not changing all that much. Acceleration is a change in velocity, and velocity is a vector quantity which means it involves both speed and direction. Since anything in orbit is changing direction at a relatively constant rate, it is constantly accelerating, but not necessarily gaining any speed.
9.8 is the rate of acceleration for objects near the surface of the Earth. It decreases as the distance increases. It's around 9 m/s² (or a little less) for the space station. I think your real question though is along what JenyApple asked though. How can you say it is constantly accelerating if it's not really getting any faster? That is because acceleration is a change in speed OR direction (or combination of both). In other words, a change in direction IS an acceleration.
Think of a change in direction as a change in speed along a single axis. The net speed over all 3 dimensional axis doesn't change, but the speed along certain axis do change. This is all a change in direction is. It is a change in speed along a specific axis. You are making this a lot more complicated than it needs to be!!!
That's not what I said. You can look at centripetal acceleration as an acceleration in the direction vector. Since acceleration is a change in velocity, and velocity contains a speed AND a direction, then a change in direction is also an acceleration. ANY change in speed, direction, or combination of the two is an acceleration. The ISS, although not constantly gaining speed, is constantly changing direction, therefore it is constantly accelerating.
Forget about speed, force is caused by acceleration. If the vessel you are in is accelerating at the same rate and in the same direction as you, then you will appear weightless. This is true for orbiting the earth at any height, and it's also true for traveling back down to the earth. If you are in an elevator that suddenly breaks loose and free falls to the ground, you will appear to be momentarily weightless within the elevator.
It came from rocket engines and boosters on liftoff and transmission into orbit. Once the orbital velocity is achieved, inertia maintains the velocity for the most part. There isn't much drag where they orbit, so they have no reason to 'slow down'. That's not to say there isn't any drag whatsoever because there is. Every so often, there are relatively minor burns that are required to correct for the little drag that does exist, but for the most part, once you get it going, it keeps on going.
I'm not an expert by any means, but I believe that centripetal force is the actual reason why they are orbitting the earth and are weightless. Since they're traveling with a horizontal velocity, the earth pulls them toward itself. This creates the orbit, which is (I think) a form of centripetal force. Since the velocity and gravitational pull are nearly equal, there is no push to the outside of the circle; otherwise the space station would sling out into space in the horizontal direction.
They are still in a state of free fall. When you throw a ball in the air, that ball is free falling for the entire flight (ignoring air resistance). If the only force acting on a body is gravity, then it is in a state of free fall. The ball is free falling on the way up as well. It is accelerating toward the Earth the entire time, and the astronauts are accelerating toward the Earth for the entire trip to the moon - and slow down all the way there.
Centripetal force is a force that acts inward and is responsible for redirecting objects into a circular path, and the force is pointing directly toward the center of rotation (or curve). If you spin a ball with a string around your head, the string exerts a centripetal force on the ball that continually redirects its path toward your hand (which acts as the center). The string remains taut because of centrifugal force, which is just the inertia of the ball wanting to continue straight. cont..
That same "tons of air" is also pushing at your feet. It's why you feel less heavy in water. However, jumping up through this medium does have a certain drag making your jump less efficient.
@felrece. The only thing that the rotation of the Earth has to do with orbits is the fact that most satellites orbit in the same direction as the Earth. The reason for this is not because the Earth's rotation has anything to do with how an object orbits, but the fact that satellites launched in the direction of rotation require less fuel to reach orbital velocity.
That moment when you watch his videos and say to yourself: From now on, I will try to do my best to listen and understand what the teacher talks about in Physics lessons, So one day we will meet, and I would (hopefully) answer almost all of his questions right!
The thinner the atmosphere, the faster an aircraft can go. For example, a 747-400 cruising at FL380 will be flying at a faster TAS than if it was flying at say, 10,000ft and require less thrust. For a 747, each of the 4 engines would have to provide some 1,500,000 pounds of thrust each for the occupants to be at a high enough speed to feel weightless in orbit.
You are on a bus traveling at a constant velocity. (velocity doesn't matter for the sake of this experiment) You jump straight up and are in the air for exactly one second. The moment you jump, the driver applies the brakes resulting in a constant acceleration of -10 m/s^2 (using negative to denote acceleration in the opposite direction of the velocity vector) You would land 10 meters toward the front of the bus from where you jumped. This experiment ignores air resistance and pixie dust.
Opps sorry. I Should have read further down. Derek gave you the correct answer. The gravitational force, hence the acceleration vector, is always perpendicular to the speed vector in a circular motion therefore it doesn't change its "length" (which is what you call the speed). You can draw a circle, take a point on it, draw the speed vector as the tangent and the force on the radius of your circle and you should see that they are perpendicular. Hence the body never 'pick up speed'.
That depends on what you define as a 'science article'. Articles in scientific journals (written by scientists) don't talk about "zero gravity", because from a physics perspective it's a nonsensical term. Science articles in newspapers and popular science magazines (written by journalists) do use that term, because it's a term their audience will recognise, whereas the correct term; 'freefall' is associated with people jumping from airplanes (who are not in freefall because of air resistance).
Acceleration is a change in velocity. Velocity is a vector quantity which means it contains both speed and direction. The ISS in orbit is constantly changing direction, therefore it is indeed accelerating. The acceleration is also a vector quantity, and it has a magnitude and a direction. The magnitude of the acceleration is equal to the acceleration due to gravity, and the direction vector is toward the center of the Earth, so it is accelerating toward the Earth.
Pretty much. The ISS however is in a low earth orbit where the atmosphere is still present, even if extremly thin, and the friction causes it to slow down very slowly. That's also why it has to make slight orbit adjustments every once in a while. But it would take ages for it to actually hit the earth(or burn up during reenter in a thicker part of the atmosphere)
In the case of the ball and the string, the centripetal force is provided by the string. In the case of orbits, the centripetal force is provided by gravity. When you are in a car and the driver turns sharply, you will feel as if you are pushed into the door. This is centrifugal force, and it acts OUTWARD (opposite to centripetal force), and is not a true force, but the result of inertia. Your body wanted to continue straight, but the car turned. The door will push you IN; that's centripetal.
In this case, the force of gravity and centripetal acceleration can be thought of as the same exact thing. The centripetal acceleration also happens to be exactly equal to the gravitational acceleration from the same elevation. The direction of centripetal acceleration is toward the center of the Earth (not opposite), just like gravity, because gravity itself is CAUSING C.A. The difference is due to the fact that the ISS is in orbit 350km high, and 9.81m/s² is the acceleration at the surface.
and that's a 100% correct intuition. still, terms like acceleration have a precise meaning in physics so we have to be careful. even though what you said is true, the object is still always accelerating towards the ground. This just doesn't have the effect that we normally think it would.
By using a little bit of clever maneuvering. First when they left the Earth, they didn't head straight toward the moon; they aimed out ahead of the moon to account for the fact that it is moving. Second, when they got close to the moon they used their thrusters to speed up and get caught by the moon's gravity. They used the moon's gravity kind of like a net.
I noticed a change in the way Derek approaches (or choose to show) people since 2 videos ago, maybe it has something to do with the "Why Do You Make People Look Stupid?" video? Anyway, I really appreciate your work, great as always!
Just for the sake of fun math, I calculated where you would need to be to make the gravitational forces counter each other. If you were to travel 346,000km of the about 384,400km (90% of the way to the moon) gravity would pull you in opposite directions with about the same force (.233 Newtons). Technically, you would be weightless, but it wouldn't last long since the moon is moving relative to you and the Earth (orbiting).
Acceleration doesn't necessarily affect the speed. It affects the velocity. The difference between those two is that speed is just how fast you are going and velocity is how fast you are going and what direction. For example, two cars driving straight away from one another at 100 km/h will have the same speed but opposite velocity since the direction is opposite. That's why ISS doesn't speed up into infinity. Gravity is only enough to change the direction of the velocity, not its largeness.
shuttles which supply the ISS also sometimes use a booster to increase the horizontal velocity of the station, keeping it in orbit. Also you assumed I did not understand even though you did not know why I thought he was wrong and as you can see I understand all of this very well.
Also, add onto this that the equator is also where the centrifugal force due to the Earth's rotation is also at the greatest. So, on Mt. Chimborazo, the combination of maximum centrifugal force (pushing outward), and minimum gravitational force would allow someone to jump the highest I suppose. Before anyone starts spamming my inbox with "centrifugal force" doesn't exist, I am well aware that centrifugal force is not a real force, but the result of inertia. It is defined that way, so I'm fine.
You are right. Centripetal force is supplied by gravity. It's not that the velocity and gravity are equal. The gravitational force depends on mass, so the force of gravity is 1000 times greater on something 1000 times more massive, yet it's orbital velocity from the same height is exactly the same as something 1000 times less massive, so there is no way the velocity and gravity could possibly be equal given this fact. You could say it is a balance between inertia/momentum and gravity.
Great questions. FYI, your logic on the train scenario is why the Earth's rotation has to be taken into account when plotting the trajectories of ballistic missiles, but like I said - height has more to do with it than the length of time you were in the air, but there WOULD be some change if you were in the air at a low height for a very long time. The 'circle' that is spinning is 6,375,000 meters in radius, and you are talking about like 1 extra meter; know what I mean?
gelukkigik, I agree with your comments about weight and being weightless. Ignore the cynical replies you received. Your mass is a constant, and your weight is a measure of your mass times the acceleration you are experiencing. When you accelerate up in an elevator you are temporarily heavier relative to the floor of the elevator. The most important thing to realize is that everything depends on perspective, and I think yours is spot on!
Thanks for actually explaining it, instead of doing what everyone else does and saying "It's because you're in freefall!" without giving any explanation whatsoever.
The trick to flying is fall, but miss the ground.
RIP Douglas Adams.
the trick is to fall with style
:PP
Well said.
the centrifugal force is complaining for not mentioning it
Hitchhiker's Guide to the Galaxyyyyyyyyyyyyyyyyy
"It's not flying, it's falling, WITH STYLE!" -Buzz Lightyear
Uhh, actually, woody said that. Not Buzz.
They actually both say it
Actually, Buzz said that. Woody said "That wasn't flying, that was-- falling with style."
Woody said it first buzz said it later not tryna be rude or anything but yeah
I would say underrated commented, but that would be overrated of me.
i love knowing the answers beforehand, i feel like a genius because of it
in the case of something orbiting, the acceleration is perpendicular to the velocity. This means it can change the direction of velocity but not its magnitude. For acceleration to cause a change in speed it must have a component in the same (or opposite) direction to velocity.
"The knack of flying is learning how to throw yourself at the ground and miss." - Douglas Adams
Now that's funny 😂😂
Richard Strosahl Isn't that a quote from The Hitchhiker’s Guide to the Galaxy?
That quote was in the book yes, which was written by Douglas Adams, which you probably knew
That quote was in the book yes, which was written by Douglas Adams, which you probably knew
+Richard Strosahl i thought exactly of that too :D
Play Kerbal Space program, easiest way to understand this.
lol so true
+niwcsc This, and get to know your apoapsis from your periapsis
I played
So true
Oh yea
As my physics lecturer would say "You are never weightless, you are however, normalforceless. It is this normalforcelessness that you call weightless. You cannot perceive weight"
i can
Now that's a masterpiece line
Your weight can be 0 but mass cant
2) One important thing to consider is that the force of gravity cannot really be felt. The only reason we have a sense of weight is because for the most part, we are all experiencing forces that COUNTER the force of gravity. So when you stand on the ground, you are not feeling the force of gravity, you are feeling the force of the ground pushing you up (usually with an equal and opposite force of gravity). When in free fall, there are no countering forces, so you FEEL weightless. but you're not.
um, we don't need gravity to digest food. Smooth muscle lining your digestive tract keeps the food moving.
Veritasium in simulated micro gravity is very creepy :P
I love the direction this show is going!! I have a feeling I'm going to be a long time subscriber!!
Such a simple concept, but did not know until I was about 50. Am 70 now. Why in the !&#* didn't one of my teachers back in the 1960s' spend just 3 minutes explaining. And this was when orbiting the earth was BIG news. Thank you Veritasium for filling some of the huge gaps.
Woah
I rarely see someone as old as you on this app(I am really sorry if it sounds rude)
I would love to be friends with you
planes don't go fast enough to "orbit". You are a little lighter 1) because you are 10km further from Earth's surface and 2) because some of your weight force is used to accelerate you in circular motion as you pass over Earth's surface.
If you are on your way to the moon, you really do reach a point where the Earth's gravity is negligible. Two Earth diameters away from Earth and your weight would be 4% of its present value (and the moon is roughly 30 Earth diameters away)
But then wouldn't you feel the gravitational pull of something else like the moon or the sun it's all bogus
@@damprotek Gravity is not something you feel directly. You feel gravity through a force that resists it, like an elevator, a rocket, a floor in a building, an airplane (that isn't falling), or the ground of the earth itself.
Every time the ISS "reboosts" itself to correct its orbit, the astronauts feel some resistance, and hence don't feel completely weightless at that moment in time.
@@gistfilm the velocity is constant, shouldnt come the time they would Stay on the "ground" of the space Station?
no, a plane and a space station have very different orbits. Planes fly at 10 km, much lower than 300km and they fly through much thicker atmosphere, making faster flying (>27000 km/h) impossible. But yes if they could go fast enough they would orbit, with weightless passengers inside.
So, would I feel the exact same sensation here on earth if I were to, say, jump off of a building while inside some type of container? The "container" is just there so I don't feel the air resistance.
yeah actually, until the container hits terminal velocity it would effectively fall at the same speed as you so relative to the container you'd be weightless.
+KingHalbatorix Not exactly. You'd need to jump off a building in a vacuum; box or not. Being inside the box doesn't eliminate drag. The drag is just on the box now, and it would NOT be in free fall in air. It doesn't accelerate at 9.8 m/s² and then all of a sudden stop accelerating at terminal velocity; the acceleration would gradually decrease as the drag force increased until it reached zero - at which point you would feel like you were just sitting on a box on the ground.
What would actually happen is you would feel weightless at first (for a split second) and you would feel heavier and heavier until you reached terminal velocity and then you'd feel as heavy as you do on the ground.
Willoughby Krenzteinburg Interesting. Thanks for the explanation.
I hope you didn't tried it :o
Just go to a theme park and get on some of the rides! That's what it should feel like all the time. Then think about it and question if you believe they are actually out there. The orbits they use are .9G free fall , NOT 0G.
I enjoy your videos, thank you for explaining in simple terms. Great Job!!
Thanks, Kerbal Space Program.
Lol I was thinking the same thing😀
Haha same here
well the space station is not that much further as a proportion of orbital radius, plus the velocity is inversely proportional to the square root of r so I think the similarity makes sense.
Hey, i really like ur videos, u make things easy to understand, can you post a video about cellular systems, no other video can be as helpful as yours!!
One of your best videos... together with that one form the park, with the huge granite ball.. Congratulations from Europe !!! CARRY ON !
Lol @ u floating. That was great as usual though :D
there are lots of places far from big masses so the gravitational force on mass would be basically zero there.
Great video! I have a follow-up question: if they are constantly accelerating towards the earth, shouldn't their velocity be increasing? Is it?
Interesting question. I don't know the answer either but is the answer somewhat similar to why the Earth's rotation around the sun and the moon's rotation around the earth are not speeding-up?
Acceleration doesn't just mean that things are speeding up or slowing down, it can also means change of direction.
There may be a distance at which our best intruments could no longer detect the gravitational pull of earth, but technically the pull of gravity extends to infinity with the force decreasing proportional to the square of the distance.
Hi,
Recently I saw the movie Gravity, I really liked it but something is really bothering me about the movie.
There is a scene where the satellite debris hit the Hubble Space Telescope and the astronaut gets loose in space, in this case, because of the gravitational forces, whouldn't the astronaut start falling into earth?
This Really Bothers Me So I Will Be Very Thankful If You Could Answer Me.
The ISS goes around the world in 90 minutes, so does the astronaut - they have a speed of 25,000 miles per hour. If the astronaut jumps off at 10 mph, she is still traveling at 25,010 mph, so she goes around the world. 90 minutes later she is only 15 miles in front of the space station and will travel like that for a year or more until air friction slows her down enough to fall to thicker air where she will burn up as a meteor.
After hearing it, this actually makes a whole lot more sense than what I thought was happening.. good1!
they turn the rocket on its side once it's left the densest part of the atmosphere
That's why railguns putting things into orbit on Earth isn't a good idea.
"How much of the atmosphere would you like to put the payload through?" Railgun- Yes
Great video. One thing that was not explained is that the space station's sideways velocity is able to prevent it from falling to Earth due to there being very little resistance from the atmosphere. If the space station were much closer to Earth, it would slow down due to atmospheric resistance and fall to Earth. It is both the sideways velocity and the lack of resistance that prevents the space station from falling to Earth.
Just out of curiosity, I calculated the orbital velocity at 10km from earth, and got 7900 m/s or 28440 km/h or 7.9 km/s. I found it surprising how close that is to the ISS's speed at 7706.6 m/s (also 27744 km/h or 7.71 km/s)
Velocity is a vector quantity with a magnitude (speed) and a direction. A change in direction is just as much an acceleration as a change in speed is, and objects in orbit are constantly changing direction. You could also call this centripetal acceleration and it is consistent with universal gravitation. For example, the acceleration of a falling body at the surface of the Earth is 9.8 m/s^2. A hypothetical object in orbit right at the surface has the same acceleration.
stopped at 1:31 .. the space station is actually free-falling... so when astronauts are floating... they are actually free falling like sky diving.. I don't know if the exact terms as to why.. but I know its free falling... let's see if I was right.
I thought the centrifugal force of orbiting neutralizes the gravitational force. it's half right, the actual phenomenon is the same but seen at a different perspective.
nextlifeonearth Nope. You've actually mixed up the different frames of reference yourself. If gravity were treated as a force that shows up in one frame of reference, then the corresponding centrifugal force only shows up in the rotating frame of reference. The two NEVER shows up in the same frame of reference and "cancel out". This is how, for example, spinning a bucket of water won't end up having water everywhere - you apply the centripetal force in your frame of reference. In the rotating frame of reference of the water, there is no centripetal force - only centrifugal force. Think about it - by your faulty analysis, if the two cancels out, the water in the bucket is weightless - it wouldn't stay in the bucket at all (and you wouldn't feel the weight of the bucket)!
All this is moot anyways, because gravity isn't really a force. All orbits are inertial paths, meaning there are no forces acting on you.
Narcissist86 you're either an idiot or really bad informed, no offence. The gravitational force of the earth would be the arm holding the bucket(satellite) and this is present, believe me. If you turn a bucket slower the water would be weightless in the bucket. (even slower and it'll get wet al over) if the satellite goes faster it'll move away from the earth(more outward centrifugal force, more acceleration, moving away) should he go slower, it'll fall to earth.
nextlifeonearth Sorry, ad hominem attacks don't work, especially when it's clear you don't know what you're talking about. I'm going to guess you have only about high school education on the matter, so it's really ironic when you call someone an idiot when there is such a large knowledge gap. But you know, you need to have SOME knowledge to know the limits of that knowledge.
As I said before, in general relativity orbits are geodesics - inertial paths through space. There are no proper forces whatsoever. So there is no need to get bogged down on wrong-minded discussions on centrifugal forces.
"If you turn a bucket slower the water would be weightless in the bucket."
Wrong. Please read up on centrifugal forces, and how it never appears in the same frame of reference as centripetal force. They never appear in the same frame to "cancel out". It's almost like you've never done free body diagrams in rotating reference frame before!
Narcissist86 calling it weightless might have been wrong, I meant relative to the bucket it would appear weightless and because of the centrifugal force it does not drop down, I asked a professor in physics if you were right, he said you were kinda right but so was I so don't try to disregard different views for the same thing. You might have understood me wrong and I apologise for calling you an idiot, but I don't like being called wrong when there are no real arguments opposing my theories.
Wow! this is the first question Veritasium has asked which i got wroong, this is awesome!
lol that urge to correct the wrong answers of the people.
Oreobility lol that urge to ask the wrong people to collect the wrong answers
the urge to defend the wrong people for being wrong, instead of acknowledging that he's teaching them something
so its falling towards the earth but because they are falling so fast it falls away from the earth and the gravitational pull keeps it at the same distant away from the earth,
The subtitles at 0:37
Who wrote those😂
🤣🤣
Ya,I also commented that!LMFAO!
?
And like I said in my very first post explaining this, it is not velocity and gravity that are in balance like you said. It is the inertia/momentum and gravity that are in balance.
Finally a video I knew all the answers for XD
Ikr
lol me too
The first video I watched and now I have been his subscriber for more than 2 years. Just revisiting old topics
did no one see the hidden message n the subtitles?
food are not floating since there is low amount of space in the stomach, its pretty tight in there. It just expand on the amount of food that get in.
yeah it affect digestion since the effect of the lack of gravity actually make foods moving very very slower through the body.
They don't shower, they use a special kind of soap that don't need water. if i remember right, its some kind of gel.
Water is vital up there, and cost a lot to carry. so they drink it instead
2:45
Sneaky audio cut ;)
Really awosome video!! Just perfect. I loved you practising the concept of science-teaching video and bringing it solidly into reality. That was a perfect ,complete scene showing the whole theoritical concept.(Y) APPRICIATE!!
YES I KNEW THIS BRFORE THIS VIDEO! I feel smart
The "need to know" is the best tool to knowledge. I see that he's explained just enough to whey the appetite for more.
How come I can't answer some peoples questions in the youtube section because there is no button?
+MrBaronmoll I think you can deactive replys. Another reason would be that the comments are too old
What Ciaran said is right. I'd just like to add this. It's surface tension will pull the molecules together and form the most efficient shape, and a sphere has the least amount of surface area for a given volume, so a sphere is the most efficient shape.
i havnt read the comments but its considered zero g not zero gravity
+Ben Capella It's literally the same thing. There is as much difference between zero g and zero gravity as there is between ABS and anti-lock brakes.
simple enough for ya
+Willoughby Krenzteinburg nah he's right g is a force and there is no force on the astronaut however there is constant gravity on the astronaut.
TONY BUI g is accelerarion, bud. G-force is a unit of apparent acceleration. 1 G-force is an apparent acceleration of 9.8 m/s^2. When standing on the surface of the Earth, your are experiencing 1 G-force. It's not a force. It's the apparent acceleration felt.
When in free fall, you experience zero G-forces. You feel zero apparent accelerations. This is what "zero g" and "zero gravity" mean. This is simple fact.
You people don't have to accept this, but you're wrong if you dont. It's really of no consequence to me either way.
+Willoughby Krenzteinburg g is not force. g is gravitational field strength or to put it in other words, force per unit mass or to put it in even simpler words, acceleration due to gravity. If a body is experiencing a force of 1g, it means that the body is accelerating at a rate of 9.81 m/s2.
Actually, while it might come off that way, he has done studies that show people learn more via video when it is presented in the way he does here (presenting the misconceptions people have to begin with, then correcting them). His name is Derek Muller. Read up on him. It's actually quite interesting. His thesis was on this. I think it is titled "Designing Effective Multimedia for Physics Education". In other words, he has done his homework and is helping people. He deserves props.
After listening to these people's answers, I now have no hope for humanity.
Lol
Those 2 guys in green tops are so cute, I could hardly concentrate, haha. Great video though. My fave so far. :)
He loves playing astronaut. Look at his expression. It's adorable.
U GOT SECOND LIKE FROM ME AFTER 8 YEARS
I love it when I already know the stuff you talk about. Or the stuff any science channel on UA-cam talks about.
Acceleration is any change in speed or direction of movement. So think of the spacestation as constantly falling towards Earth and just missing the ground. It keeps changing its direction because when it gets to the other side of the Earth, it's now being pulled a different direction. That means it has "accelerated" because it's being pulled in a different direction.
Acceleration is a change in velocity. Velocity is a vector quantity, which means it has both speed and a direction. Objects in orbit are constantly changing direction (since they are orbiting in a circular trajectory), therefore they are accelerating. A change in direction is just as much an acceleration as a change in speed is.
They are constantly accelerating toward the center of Earth. That is the force vector, so the acceleration vector points toward the center of Earth as well. The important thing to understand is that acceleration is a vector quantity, which means it has a magnitute (velocity) and a direction. This means that a change in direction is just as much an acceleration as a change in velocity is. At any given instant, the ISS is accelerating (changing direction) toward the center of Earth.
this is alot better than other videos ive seen i kinda stopped watching because he would spent 5 mins asking people questions and getting wrong answers then finally after 5 mins get the answer. but this is good pace few answers and then he answers it
You should try to get these episodes on some science channel, they are brilliant and really teaches fun stuff that regular people can enjoy and apprieciate!
Wah animations!!! Productions value +5. Loved it before, love it now. Keep up the great work!
Fabulous explanation! I watched 10 videos before this but only you made me understand. You've earned yourself a new subscriber :)
Your videos get better with every one. Thanks for this great information. :-)
Yes, there is still some force when "swimming", I'm just not sure if it's getting you anywhere within a reasonable amount of time.
Thanks.
Acceleration is also a vector quantity, with a magnitude and direction as well. Objects in orbit are constantly accelerating (changing direction), and the acceleration vector is pointed toward the center of the Earth. This is why you say that objects in orbit are constantly accelerating toward the center of the Earth.
To answer your question, if you were to drop a rock from an elevation equal to where the ISS orbits, the acceleration of the rock, and the acceleration of the ISS would be identical. It's just that the rock accelerates in a linear fashion (acceleration only affects speed), and the ISS is accelerating angularly (centripetal acceleration), but the accerations are the same. If you ignored air resistance, and put something in orbit near the surface, its centripetal acceleration would be 9.8m/s².
The first cosminc speed would be the velocity required to orbit the Earth right at the surface. It obviously ignores any drag. The second cosmic speed is the escape velocity of the Earth, and the third cosmic speed is the escape velocity of the sun.
@everyday420ful. They are accelerating at a constant rate, but their speed is not changing all that much. Acceleration is a change in velocity, and velocity is a vector quantity which means it involves both speed and direction. Since anything in orbit is changing direction at a relatively constant rate, it is constantly accelerating, but not necessarily gaining any speed.
9.8 is the rate of acceleration for objects near the surface of the Earth. It decreases as the distance increases. It's around 9 m/s² (or a little less) for the space station. I think your real question though is along what JenyApple asked though. How can you say it is constantly accelerating if it's not really getting any faster? That is because acceleration is a change in speed OR direction (or combination of both). In other words, a change in direction IS an acceleration.
Think of a change in direction as a change in speed along a single axis. The net speed over all 3 dimensional axis doesn't change, but the speed along certain axis do change. This is all a change in direction is. It is a change in speed along a specific axis. You are making this a lot more complicated than it needs to be!!!
That's not what I said. You can look at centripetal acceleration as an acceleration in the direction vector. Since acceleration is a change in velocity, and velocity contains a speed AND a direction, then a change in direction is also an acceleration. ANY change in speed, direction, or combination of the two is an acceleration. The ISS, although not constantly gaining speed, is constantly changing direction, therefore it is constantly accelerating.
Forget about speed, force is caused by acceleration. If the vessel you are in is accelerating at the same rate and in the same direction as you, then you will appear weightless. This is true for orbiting the earth at any height, and it's also true for traveling back down to the earth. If you are in an elevator that suddenly breaks loose and free falls to the ground, you will appear to be momentarily weightless within the elevator.
It came from rocket engines and boosters on liftoff and transmission into orbit. Once the orbital velocity is achieved, inertia maintains the velocity for the most part. There isn't much drag where they orbit, so they have no reason to 'slow down'. That's not to say there isn't any drag whatsoever because there is. Every so often, there are relatively minor burns that are required to correct for the little drag that does exist, but for the most part, once you get it going, it keeps on going.
Loved the new editing!
I'm not an expert by any means, but I believe that centripetal force is the actual reason why they are orbitting the earth and are weightless. Since they're traveling with a horizontal velocity, the earth pulls them toward itself. This creates the orbit, which is (I think) a form of centripetal force. Since the velocity and gravitational pull are nearly equal, there is no push to the outside of the circle; otherwise the space station would sling out into space in the horizontal direction.
They are still in a state of free fall. When you throw a ball in the air, that ball is free falling for the entire flight (ignoring air resistance). If the only force acting on a body is gravity, then it is in a state of free fall. The ball is free falling on the way up as well. It is accelerating toward the Earth the entire time, and the astronauts are accelerating toward the Earth for the entire trip to the moon - and slow down all the way there.
Centripetal force is a force that acts inward and is responsible for redirecting objects into a circular path, and the force is pointing directly toward the center of rotation (or curve). If you spin a ball with a string around your head, the string exerts a centripetal force on the ball that continually redirects its path toward your hand (which acts as the center). The string remains taut because of centrifugal force, which is just the inertia of the ball wanting to continue straight. cont..
Wow, love your channel, your doing a great job of explaining science to people, well done :o)
That same "tons of air" is also pushing at your feet. It's why you feel less heavy in water. However, jumping up through this medium does have a certain drag making your jump less efficient.
@felrece. The only thing that the rotation of the Earth has to do with orbits is the fact that most satellites orbit in the same direction as the Earth. The reason for this is not because the Earth's rotation has anything to do with how an object orbits, but the fact that satellites launched in the direction of rotation require less fuel to reach orbital velocity.
you finally did it! :) nice video derek!
That moment when you watch his videos and say to yourself:
From now on, I will try to do my best to listen and understand what the teacher talks about in Physics lessons,
So one day we will meet, and I would (hopefully) answer almost all of his questions right!
The thinner the atmosphere, the faster an aircraft can go. For example, a 747-400 cruising at FL380 will be flying at a faster TAS than if it was flying at say, 10,000ft and require less thrust. For a 747, each of the 4 engines would have to provide some 1,500,000 pounds of thrust each for the occupants to be at a high enough speed to feel weightless in orbit.
You are on a bus traveling at a constant velocity. (velocity doesn't matter for the sake of this experiment)
You jump straight up and are in the air for exactly one second.
The moment you jump, the driver applies the brakes resulting in a constant acceleration of -10 m/s^2 (using negative to denote acceleration in the opposite direction of the velocity vector)
You would land 10 meters toward the front of the bus from where you jumped.
This experiment ignores air resistance and pixie dust.
I've always loved that pseudo-weightlessness you get during a massive drop on roller coasters or something else of the sort.
Shut the hell up Drew Jones
Opps sorry. I Should have read further down. Derek gave you the correct answer. The gravitational force, hence the acceleration vector, is always perpendicular to the speed vector in a circular motion therefore it doesn't change its "length" (which is what you call the speed). You can draw a circle, take a point on it, draw the speed vector as the tangent and the force on the radius of your circle and you should see that they are perpendicular. Hence the body never 'pick up speed'.
That depends on what you define as a 'science article'. Articles in scientific journals (written by scientists) don't talk about "zero gravity", because from a physics perspective it's a nonsensical term. Science articles in newspapers and popular science magazines (written by journalists) do use that term, because it's a term their audience will recognise, whereas the correct term; 'freefall' is associated with people jumping from airplanes (who are not in freefall because of air resistance).
Acceleration is a change in velocity. Velocity is a vector quantity which means it contains both speed and direction. The ISS in orbit is constantly changing direction, therefore it is indeed accelerating. The acceleration is also a vector quantity, and it has a magnitude and a direction. The magnitude of the acceleration is equal to the acceleration due to gravity, and the direction vector is toward the center of the Earth, so it is accelerating toward the Earth.
Pretty much. The ISS however is in a low earth orbit where the atmosphere is still present, even if extremly thin, and the friction causes it to slow down very slowly. That's also why it has to make slight orbit adjustments every once in a while. But it would take ages for it to actually hit the earth(or burn up during reenter in a thicker part of the atmosphere)
In the case of the ball and the string, the centripetal force is provided by the string. In the case of orbits, the centripetal force is provided by gravity. When you are in a car and the driver turns sharply, you will feel as if you are pushed into the door. This is centrifugal force, and it acts OUTWARD (opposite to centripetal force), and is not a true force, but the result of inertia. Your body wanted to continue straight, but the car turned. The door will push you IN; that's centripetal.
In this case, the force of gravity and centripetal acceleration can be thought of as the same exact thing. The centripetal acceleration also happens to be exactly equal to the gravitational acceleration from the same elevation. The direction of centripetal acceleration is toward the center of the Earth (not opposite), just like gravity, because gravity itself is CAUSING C.A. The difference is due to the fact that the ISS is in orbit 350km high, and 9.81m/s² is the acceleration at the surface.
and that's a 100% correct intuition. still, terms like acceleration have a precise meaning in physics so we have to be careful. even though what you said is true, the object is still always accelerating towards the ground. This just doesn't have the effect that we normally think it would.
By using a little bit of clever maneuvering. First when they left the Earth, they didn't head straight toward the moon; they aimed out ahead of the moon to account for the fact that it is moving. Second, when they got close to the moon they used their thrusters to speed up and get caught by the moon's gravity. They used the moon's gravity kind of like a net.
I noticed a change in the way Derek approaches (or choose to show) people since 2 videos ago, maybe it has something to do with the "Why Do You Make People Look Stupid?" video?
Anyway, I really appreciate your work, great as always!
Just for the sake of fun math, I calculated where you would need to be to make the gravitational forces counter each other. If you were to travel 346,000km of the about 384,400km (90% of the way to the moon) gravity would pull you in opposite directions with about the same force (.233 Newtons). Technically, you would be weightless, but it wouldn't last long since the moon is moving relative to you and the Earth (orbiting).
Acceleration doesn't necessarily affect the speed. It affects the velocity. The difference between those two is that speed is just how fast you are going and velocity is how fast you are going and what direction. For example, two cars driving straight away from one another at 100 km/h will have the same speed but opposite velocity since the direction is opposite. That's why ISS doesn't speed up into infinity. Gravity is only enough to change the direction of the velocity, not its largeness.
shuttles which supply the ISS also sometimes use a booster to increase the horizontal velocity of the station, keeping it in orbit. Also you assumed I did not understand even though you did not know why I thought he was wrong and as you can see I understand all of this very well.
Also, add onto this that the equator is also where the centrifugal force due to the Earth's rotation is also at the greatest. So, on Mt. Chimborazo, the combination of maximum centrifugal force (pushing outward), and minimum gravitational force would allow someone to jump the highest I suppose. Before anyone starts spamming my inbox with "centrifugal force" doesn't exist, I am well aware that centrifugal force is not a real force, but the result of inertia. It is defined that way, so I'm fine.
You are right. Centripetal force is supplied by gravity.
It's not that the velocity and gravity are equal. The gravitational force depends on mass, so the force of gravity is 1000 times greater on something 1000 times more massive, yet it's orbital velocity from the same height is exactly the same as something 1000 times less massive, so there is no way the velocity and gravity could possibly be equal given this fact. You could say it is a balance between inertia/momentum and gravity.
Great questions. FYI, your logic on the train scenario is why the Earth's rotation has to be taken into account when plotting the trajectories of ballistic missiles, but like I said - height has more to do with it than the length of time you were in the air, but there WOULD be some change if you were in the air at a low height for a very long time. The 'circle' that is spinning is 6,375,000 meters in radius, and you are talking about like 1 extra meter; know what I mean?
gelukkigik, I agree with your comments about weight and being weightless. Ignore the cynical replies you received.
Your mass is a constant, and your weight is a measure of your mass times the acceleration you are experiencing. When you accelerate up in an elevator you are temporarily heavier relative to the floor of the elevator. The most important thing to realize is that everything depends on perspective, and I think yours is spot on!