Linky Link, Cool. Quite the co-inkydink. Thanks for the comment, and keep up with the physics! You might also like my new website: www.universityphysics.education Cheers, Dr. A
I had this EXACT question burning in my head for a few days now and so glad to see the final answer here! I am very proud to say that I guessed it correctly. But I believe the equation will be true only in total vacuum? I wonder how aerodynamics can effect bullets of different shapes? Anyway, thanks very much for posting this video professor. 👍👍
considering the curvature of the general bullets body, wouldnt aerodynamics, ie the drag factor on the bullet when travelling through air, have a minimal affect on the time taken for the bullet to hit the ground? especially when considering drag plays a part when dropping bullet number 2 in the same atmosphere? please correct me if im mistaken
From my training as a solider ive also been taught that a bullet will rise before up amd to the right a few inches due to rotation of the bullet more like an arch than a flat trajectory that drops off
A gunner on a coast made a direct hit on the ship 10 miles away. If the angle of projection above the horizontal is 60o, find: (a) the velocity of the projectile when it struck the ship (b) the vertical position of the projectile 20 seconds after.
An interesting thought here about the earth curvature. If you have the same problem or setup but in addition have a laser beam on the ground in the bullets direction. In this theoretical experiment the fired bullet is able to travel, let’s say 50 miles. In my opinion the fired bullet will cross the laser beam first (?)
You can do this experiment in real life safely. We had a big gun that fired a wooden bullet thay was tensioned by a rubber cord. At he end of the barrel was a bit of tin foil. This foil was a conductor for an electro magnet at the end of the room. This electro magnet held up a target. When the bullet is fired, as it leave the barrel it breaks the foil and starts to drop with gravity. The target at end of the room also starts to drop as the foil has been broken. So both the bullet and he target are falling. Both fall at he same rate so the bullet hit the target. No matter how fast or slow we made the bullet go, as long as the bullet had enough power to make the distance to the target, it always hit the target. It proved the point a bullet falls at the same speed as something that was dropped.
Geeze, my formula is "velocity x .6 = the distance a level fired bullet, at 5' high, hits the ground. A bullet used has a velocity of 800fps.. so, 800 x .6 = 480' . A bullet dropped AND fired both will land less than .5 of a second. Gravity.
Poncho Villa, Ahhh math humor, can't get enough of it. Thanks for the comment, and keep up with the physics! You might also like my new website: www.universityphysics.education Cheers, Dr. A
The bullet dropped would land first it is quite simple A considerable portion of a bullet is propellant, a bullet fired would be without propellant and therefore have less weight.
This is actually not correct, you are only accounting for the physical force of gravity and not accounting for aerodynamic effects. of which there are several that will cause the fired bullet to land slightly later than the dropped bullet. A fired bullet typically has a very high spin rate (150,000 to 300,00 RPM) and thus has a very large amount of gyroscopic energy that acts on a counter-intuitive CG/CP arm. The CP (center of pressure) is forward of the CG (center of gravity) and thus as the fired bullet descends into the increasingly upward relative wind, There is an upward force on the forward CP countering a downward force acting on the CG, creating a nose-up force on the bullet. Gyroscopic precession translates this force into a yaw in the direction of the bullet's spin, usually the right. This is not "free" energy, some of the gravitational energy is consumed. This increases with range, at 1,000 yards about 3% of the bullet's drop will have been converted into right yaw, meaning that the bullet will land 3% later than the dropped bullet. There's other artifacts too, the dropped bullet falls base-first with a lower drag profile where gyroscopic rigidity will cause the fired bullet to remain horizontal and fall through the air with a higher drag profile in the vertical component. This would be much smaller. Also, there's potentially shock wave compression under the fired bullet that creates a potential ground effect.
I have been digging through his videos and have not seen an example that includes ballistic coefficient into the equations. Granted that would not effect this example very much but in his other problems it would. Even those examples that only explore 250 meters need to take this into account. BC won't effect the drop, it only affects the retained velocity. A higher retained velocity means the bullet will travel farther over a given period of time therefore will have less time to have fallen when it gets to that point. i.e. a higher BC bullet gets there faster so it has less time to fall at the g constant.
I just have one more thought to this in my head. say for instance the bullet shot was a bullet of very high velocity. would it not take longer for a bullet with a higher velocity to begin to drop? it would have a longer trajectory and therefore a longer flight time?
Well the propellant decides the dropping time a 45 cal bullet will come to ground much later than 45 cal dropped by hand...the propellant pushing bullet makes it act against the gravity and more the propellant less the effect of gravity.
Anhad, Yes we need to ignore any air resistance and also need to ignore any propulsion of the bullet that is not perfectly horizontal. So we need to ignore a lot of stuff. But that's what physicists do. You might also like my new website: www.universityphysics.education Cheers, Dr. A
Hey Dr. A, I have a question. Isn't the x direction kinematic equation unnecessary since the y direction equation already proves that the bullets fall to the ground at the same time?
1- at the instant a gun fires bullet horizontally, an identical bullet is dropped from rest vertically to the ground. Which one hits the ground first? Expkain 2- want would be the trajectory of the projectile of gravity ere zeros?
NO, it is incorrect! all bullets and cartridges are not created equal, the ballistic coefficient makes a big difference on how long and how flat the bullet will travel along with the velocity; for instance a 6.5- 300 Weatherby with 140 grain bullet is going to go a lot further then the 30/30 and stay in the air a lot longer. When he said if "you shoot a bullet a long ways, like the distance of a football field!" A football field is not a long ways to fire a bullet, maybe a musket. This might be correct if you are shooting round musket balls not. 140 grain 6.5 mm with a balistic coefficient of 650.
Perhaps it is. You can probably get a level in the sight I imagine. Remember to take what I say with a grain of salt. Like the old bumper sticker says: Question Authority. Cheers, Dr. A
Doungeon.rapper, Of course. Projectile motion is derived from basic kinematics. Thanks for the comment, and keep up with the physics! You might also like my new website: www.universityphysics.education Cheers, Dr. A
But ummmmm if h was 245 KM and the earth did not have an atmosphere, given the X(initial) of bullet #1 was 27,400KM/h then we will have a problem with the formula because the two bullets will not hit the earth surface at the same time, or will they?
they wouldnt the fired bullet will hit the "ground" last because of the curvature of the earth. If the bullet was fired such as in a vaccum with perpectly smooth surface at 18,000 thousand miles an hour the fired bullet would NEVER hit the ground
NATURAL GAMER, Not writing backwards (I'm not that talented). The board is called Learning Glass. You can check it out at www.learning.glass Cheers, Dr. A
Bullets do not generate lift. Their cross-section is symmetrical, so air travels at the same speed over and under the bullet. The reason a wing generates lift is that air has to pass over the wing faster than it does under the wing, creating a pressure difference.
@@faust82 if he is talking about the recoil from the gun, that whud not change anything. Beceuse lets say from a pistol, the recoil will kick in after the bullet has left the barrel of the gun. Yes the same amount of force forward is going backwords, that doesnt effect the bullet.
I don't get it. I have two questions: Why do you add Xi and Yi to the formula? Shouldn't it be without it? Why is the ½at² = 0 on the bullet 1 in X formula? Shouldn't it has numbers because the bullet gains acceleration due to gravity?
That’s why he wrote a y equations gravity works in up in down direction, thus y axis. So I’m the x formula gravity does no accelerating because gravity won’t accelerate the bullet to the right or left
If they would hit the ground at the same time how would it be possible to get anything in orbit. So a Moon that is in orbit at 2200 miles per hours would take the same time to hit the earth as a moon that is moving at 0 miles per hour.
Excellent point. In this example, we're using the flat earth approximation. As you alluded to, on a round earth if you shot the bullet fast enough, it would go into orbit. In fact, if you calculate what speed that would be, it turns out to be around 17,000 mph. Cheers, Dr. A
I had similar thoughts. Speed is what keep satellites in orbit. This example would only work in a "flat earth" scenario. The momentum adds to its centrifugal force. My argument may revolve around the premise and that example is not an accurate example of firing a bullet on Earth. IF speed can keep a satellite in orbit it's going to effect a bullet too, even if it's hard to measure, there will be a difference. Thoughts welcomed :)
Bullets that are rotating (spindrift). There is a small additional displacement downward and to the right. Need to add Ysd (vertical) to your equation. It is a small amount, but should be at least mentioned.
It's about gravity and has nothing to do whith horizontal speed. 2 identical object are affected identcally by gravity. They both hit the ground in the same milisecond, even if one was projected hundreds of meters/feet away horizontaly.
The bullet that's been fired will reach the ground 1st regardless of the calibre of the gun, because it'll have a greater force than gravity (the intertia from the firearm) acting on it in the same direction, terminal velocity which is the top speed of something falling with only gravity acting on it is only around 180mph, whereas guns can project a bullet up to 3,000mph
Does that mean that bullet 1 falls faster than bullet 2? It takes some time to travel horizontally so in order to reach the ground at the same time it needs to drop faster? Or is the drawing incorrect and the descent is in fact starting immediately?
Picture might not be the best, but no - both bullets drop at the same rate vertically so they both hit the ground at the same time (the caveat, of course, is that you have to fire the bullet PERFECTLY horizontal). Cheers, Dr. A
Gravity acts on both bullets in the same direction and with the same force over the same amount of time (because the release height is identical) - irrespective of the horizontal velocity. The vertical component is not affected by horizontal movement.
Judah, Then of course the bullet shot upwards at 45˚ would be in the air longer. Not too difficult to calculate how long it would be in the air. See, for example: ua-cam.com/video/ZPaRFr_3g2k/v-deo.html Cheers, Dr. A
Wrextoration, I'm a peace lover by trade. Not sure why we have such morbid examples in physics. Thanks for the comment, and keep up with the physics! You might also like my new website: www.universityphysics.education Cheers, Dr. A
Yes all bullets and cartridges are not created equal, the ballistic coefficient makes a big difference on how long and how flat the bullet will travel along with the velocity; for instance a 6.5- 300 Weatherby with 140 grain bullet is going to go a lot further then the 30/30 and stay in the air a lot longer. When he said if "you shoot a bullet a long ways, like the distance of a football field!" A football field is not a long ways to fire a bullet, maybe a musket. This might be correct if you are shooting round musket balls not. 140 grain 6.5 mm with a balistic coefficient of 650.
I had this coversation with a friend of mine last week who was convinced that the bullet fired from the gun at a 90 degree angle would reach the ground at the same time as the bullet dropped from the same height at 180 degrees...but...it...doesn't (Once the bullet that's been fired loses all inertian and begins to fall with nothing acting on it but gravity, that's when it will meet the ground at the same time as the one dropped) I was explaining to him that according to chaos theory there were too many variables in 1. The angle of firing horizontally 2. Calibre of the gun which affects the speed and range of the bullet fired 3. The type of ammunition used as match-grade ammunition can be used to permit a far greater range 4. Wind resistance on the fired bullet compared to the one dropped, for this to be an accurate claim What I did was draw the exact same diagram you have, only I pointed out the exact moments that were mathmatically sound (the full motion of the bullet being dropped and the falling motion of the bullet fired once it's lost all intertia and has only the superior force of gravity acting on it till it reaches the ground) It's NOT true or mathmatically sound that a bullet fired horizontally will reach the ground at the same time as one dropped from the same height, because of the different ranges and speeds of different calibre firearms along with the inevitable difference in air pressure and resistance between the area you're dropping one and the area the fired one is in once it begins to fall
Gosh... I hope nobody takes what you wrote seriously. As soon as a bullet leaves the barrel, it is falling. A bullet has no "lift"... a bullet appears to travel in a decreasing radius arc that leads people to believe that it's not falling at first, but it is. That decreasing radius is due to the decreasing speed... but the rate of fall for the bullet is the same.
your mistaken and wind does not count for the purpose of the thought experiement of course. it could be done in a vaccum. The bullet fired from the gun hits last because the earth is curving away and dropping below the bullet. It passes through the straight plane drawn at the same time but it hits the GROUND last.
This guy must be a flat earther. He ignores that the earth is curved. Yes, both fall at the same rate but the bullet that has been fired has further to fall.
Sandra Melodie Navarro, Yes. Thanks for the comment, and keep up with the physics! You might also like my new website: www.universityphysics.education Cheers, Dr. A
Wouldn't air resistance come into play here? When the bullet is fired, air hits the front of the bullet and the bullet remains in the same orientation; However, when the bullet is dropped, it will not maintain the same orientation and air will hit the underside of the bullet which has a greater surface area or it may even tumble which means greater air resistance resulting in a longer fall time. They would only hit the ground at the same time if they were in a vacuum. There is also the delay in the time it takes for the bullet to leave the inside of the barrel when it isn't falling, as well as the time it takes for the firing pin to strike the primer once the trigger is pulled.
He's says as soon as it leaves the gun... He isn't calculating time in barrel, primer, time thinking about shooting, loading the gun, or time waiting for background check.
You said which will hit the ground first? The dropped bullet will hit the ground first. Obviously figure the earth is a perfect smooth sphere and discount air or wind such as even in a vaccum. You drew a straight plane. Both bullets would pass through that plane at the same time assuming the fired bullet did not hit a plane. However the earth is round and the one fired from the gun the earth is curving downward away from it same as orbit concept and the old drawing of a cannon on a mountaintop that shoots cannon ball at 18 thousand miles per hour and of course it never hits. Thus the rifle bullet hits LAST. so for the sake of the experiment it has to be tweaked for the class to discount the curvature of the earth and instead say "which bullet will pass through this flat plane first?" not "hit the ground". but I understand the purpose of the thought experiment so I will let this one slide. so a person could make thousands of dollars on this bet over a lifetime. Your welcome in advance. I could ask it to Albert Einstein with thousand dollar bet and he would say "this dosent count! you tricked me! you know what I meant"!!
thợ săn xó bêp, Thanks for the comment, and keep up with the physics! You might also like my new website: www.universityphysics.education Cheers, Dr. A
Depending on the caliber and firearm, you can set horizontal initial velocity to 800m/s (~2600 feet/s), which would be fairly typical for a .308win rifle with a heavier bullet (175gr, or 11 grams). Vertical initial velocity is 0, and both bullets accelerate towards the ground at approximately 9.81m/s²
I know this guy is very intelligent but what impressed me the the most is his ability to write backwards.
Lol dude... just write normally and mirror the video. It's not that hard...
@@emmygee2156Prolly a joke
Thanks Dr. A, you've helped me win a £2 bet.
Excellent. Don't spend it all in one place. Unless it's the pub. Then definitely do.
Cheers,
Dr. A
instablaster.
When he was writing on the board that sqeek sound made me think there was a mouse in my room
This randomly popped into my head this morning. Thanks for answering!
Linky Link,
Cool. Quite the co-inkydink.
Thanks for the comment, and keep up with the physics!
You might also like my new website: www.universityphysics.education
Cheers,
Dr. A
I can't write that well the right way around and you're writing that backwards.
Teach me _that_.
Not exactly: www.learning.glass
Cheers,
Dr. A
There go my hopes and dreams :(
Sorry. Physics has a way of ruining magic.
Cheers,
Dr. A
Professor, I love the 0=0 lesson. You are so funny and intelligent.
Funny=intelligent
I had this EXACT question burning in my head for a few days now and so glad to see the final answer here!
I am very proud to say that I guessed it correctly.
But I believe the equation will be true only in total vacuum?
I wonder how aerodynamics can effect bullets of different shapes?
Anyway, thanks very much for posting this video professor. 👍👍
Whudnt the bullet from the gun not go of in the vaccum beceuse the guns bullet need fire to make it move forword?
considering the curvature of the general bullets body, wouldnt aerodynamics, ie the drag factor on the bullet when travelling through air, have a minimal affect on the time taken for the bullet to hit the ground? especially when considering drag plays a part when dropping bullet number 2 in the same atmosphere? please correct me if im mistaken
actually thats not true. due to the curvature of the earth the fired bullet travels further vertically than the dropped bullet
From my training as a solider ive also been taught that a bullet will rise before up amd to the right a few inches due to rotation of the bullet more like an arch than a flat trajectory that drops off
This isn’t true. Perceived rise is only due to sight calibration.
Also a bullet that is fired no longer has propellant attached to it, so it weighs less
A gunner on a coast made a direct hit on the ship 10 miles away. If the angle of projection above the horizontal is 60o, find: (a) the velocity of the projectile when it struck the ship (b) the vertical position of the projectile 20 seconds after.
An interesting thought here about the earth curvature. If you have the same problem or setup but in addition have a laser beam on the ground in the bullets direction. In this theoretical experiment the fired bullet is able to travel, let’s say 50 miles. In my opinion the fired bullet will cross the laser beam first (?)
You can do this experiment in real life safely.
We had a big gun that fired a wooden bullet thay was tensioned by a rubber cord. At he end of the barrel was a bit of tin foil. This foil was a conductor for an electro magnet at the end of the room. This electro magnet held up a target.
When the bullet is fired, as it leave the barrel it breaks the foil and starts to drop with gravity. The target at end of the room also starts to drop as the foil has been broken. So both the bullet and he target are falling. Both fall at he same rate so the bullet hit the target.
No matter how fast or slow we made the bullet go, as long as the bullet had enough power to make the distance to the target, it always hit the target.
It proved the point a bullet falls at the same speed as something that was dropped.
In layman’s terms gravity is a constant force pulling on both objects equally
Geeze, my formula is "velocity x .6 = the distance a level fired bullet, at 5' high, hits the ground. A bullet used has a velocity of 800fps.. so, 800 x .6 = 480' . A bullet dropped AND fired both will land less than .5 of a second. Gravity.
The reason this doesn't seem true in real life is because guns actually fire in an upward trajectory, not perfectly horizontal
oh lord.
"0=0, no matter how many 0's you add to it." I don't know why but this made me laugh
Poncho Villa,
Ahhh math humor, can't get enough of it.
Thanks for the comment, and keep up with the physics!
You might also like my new website: www.universityphysics.education
Cheers,
Dr. A
The bullet dropped would land first
it is quite simple
A considerable portion of a bullet is propellant, a bullet fired would be without propellant and therefore have less weight.
Wonderful lecturer that makes physics fun and understandable !!!
I was afraid I'd be the only one that caught the backwards writing
Thank you Doc this really helped me understand!
This is actually not correct, you are only accounting for the physical force of gravity and not accounting for aerodynamic effects. of which there are several that will cause the fired bullet to land slightly later than the dropped bullet. A fired bullet typically has a very high spin rate (150,000 to 300,00 RPM) and thus has a very large amount of gyroscopic energy that acts on a counter-intuitive CG/CP arm. The CP (center of pressure) is forward of the CG (center of gravity) and thus as the fired bullet descends into the increasingly upward relative wind, There is an upward force on the forward CP countering a downward force acting on the CG, creating a nose-up force on the bullet. Gyroscopic precession translates this force into a yaw in the direction of the bullet's spin, usually the right. This is not "free" energy, some of the gravitational energy is consumed. This increases with range, at 1,000 yards about 3% of the bullet's drop will have been converted into right yaw, meaning that the bullet will land 3% later than the dropped bullet. There's other artifacts too, the dropped bullet falls base-first with a lower drag profile where gyroscopic rigidity will cause the fired bullet to remain horizontal and fall through the air with a higher drag profile in the vertical component. This would be much smaller. Also, there's potentially shock wave compression under the fired bullet that creates a potential ground effect.
Excellent stuff. And yes, we are treating a rather simplified version.
Thank you.
Cheers,
Dr. A
I have been digging through his videos and have not seen an example that includes ballistic coefficient into the equations. Granted that would not effect this example very much but in his other problems it would. Even those examples that only explore 250 meters need to take this into account. BC won't effect the drop, it only affects the retained velocity. A higher retained velocity means the bullet will travel farther over a given period of time therefore will have less time to have fallen when it gets to that point. i.e. a higher BC bullet gets there faster so it has less time to fall at the g constant.
I just have one more thought to this in my head. say for instance the bullet shot was a bullet of very high velocity. would it not take longer for a bullet with a higher velocity to begin to drop? it would have a longer trajectory and therefore a longer flight time?
Not if it is also fired perfectly horizontally (and we ignore a round earth).
Cheers,
Dr. A
great explanation. what material do you use to write on? is that glass or Plexiglas?
Real glass. Check it out here: www.learning.glass
Cheers,
Dr. A
He looks like the more mature version of Freddie Highmore. You'll have a better idea of what I'm talking about if you watched the "August Rush" movie.
Well the propellant decides the dropping time a 45 cal bullet will come to ground much later than 45 cal dropped by hand...the propellant pushing bullet makes it act against the gravity and more the propellant less the effect of gravity.
engineering innovation & design is to thank for that, i'm sure in this example he means for the bullets to ignore air resistance
Anhad,
Yes we need to ignore any air resistance and also need to ignore any propulsion of the bullet that is not perfectly horizontal. So we need to ignore a lot of stuff. But that's what physicists do.
You might also like my new website: www.universityphysics.education
Cheers,
Dr. A
🤘😝🤘fantastic... You teach and lecture very well. Wished we had like you in school days...
Cheers 🍻 to physics n you 🍾
Hey Dr. A, I have a question. Isn't the x direction kinematic equation unnecessary since the y direction equation already proves that the bullets fall to the ground at the same time?
1- at the instant a gun fires bullet horizontally, an identical bullet is dropped from rest vertically to the ground. Which one hits the ground first? Expkain
2- want would be the trajectory of the projectile of gravity ere zeros?
is this guy writing backwards???
Thank you Matt
NO, it is incorrect! all bullets and cartridges are not created equal, the ballistic coefficient makes a big difference on how long and how flat the bullet will travel along with the velocity; for instance a 6.5- 300 Weatherby with 140 grain bullet is going to go a lot further then the 30/30 and stay in the air a lot longer. When he said if "you shoot a bullet a long ways, like the distance of a football field!" A football field is not a long ways to fire a bullet, maybe a musket. This might be correct if you are shooting round musket balls not. 140 grain 6.5 mm with a balistic coefficient of 650.
Also it is very easy to achieve a accurate horizontal firing line. Being lied to again
Perhaps it is. You can probably get a level in the sight I imagine.
Remember to take what I say with a grain of salt. Like the old bumper sticker says: Question Authority.
Cheers,
Dr. A
Can this be explained without the projectile basics and using basic kinematics.
Doungeon.rapper,
Of course. Projectile motion is derived from basic kinematics.
Thanks for the comment, and keep up with the physics!
You might also like my new website: www.universityphysics.education
Cheers,
Dr. A
But ummmmm if h was 245 KM and the earth did not have an atmosphere, given the X(initial) of bullet #1 was 27,400KM/h then we will have a problem with the formula because the two bullets will not hit the earth surface at the same time, or will they?
they wouldnt the fired bullet will hit the "ground" last because of the curvature of the earth. If the bullet was fired such as in a vaccum with perpectly smooth surface at 18,000 thousand miles an hour the fired bullet would NEVER hit the ground
are you mirrored whole video or
you can write backward so perfectly sir
NATURAL GAMER,
Not writing backwards (I'm not that talented). The board is called Learning Glass. You can check it out at www.learning.glass
Cheers,
Dr. A
@@yoprofmatt
Thanks SIR for your replay
What about the lift that is generated on bullet no 2
Sorry i mean bullet no 1
What lift? .. you think that bullets start to rise when fired out of a gun? Does a dart have lift?
Bullets do not generate lift. Their cross-section is symmetrical, so air travels at the same speed over and under the bullet.
The reason a wing generates lift is that air has to pass over the wing faster than it does under the wing, creating a pressure difference.
@@faust82 if he is talking about the recoil from the gun, that whud not change anything. Beceuse lets say from a pistol, the recoil will kick in after the bullet has left the barrel of the gun. Yes the same amount of force forward is going backwords, that doesnt effect the bullet.
Thank you Sir.
lamprospan,
You're very welcome. Glad you're enjoying the videos.
You might also like my new site: www.universityphysics.education
Cheers,
Dr. A
I don't get it. I have two questions:
Why do you add Xi and Yi to the formula? Shouldn't it be without it?
Why is the ½at² = 0 on the bullet 1 in X formula? Shouldn't it has numbers because the bullet gains acceleration due to gravity?
That’s why he wrote a y equations gravity works in up in down direction, thus y axis. So I’m the x formula gravity does no accelerating because gravity won’t accelerate the bullet to the right or left
Kafka Adhyaksa,
Not sure I can answer that here, but come visit me on my new website: www.universityphysics.education
Cheers,
Dr. A
Wow I just realized I’m literally a dumbass. Couldn’t understand 1% of this math...
Asians have finished learning this stuff in middle school
If they would hit the ground at the same time how would it be possible to get anything in orbit. So a Moon that is in orbit at 2200 miles per hours would take the same time to hit the earth as a moon that is moving at 0 miles per hour.
Excellent point. In this example, we're using the flat earth approximation. As you alluded to, on a round earth if you shot the bullet fast enough, it would go into orbit. In fact, if you calculate what speed that would be, it turns out to be around 17,000 mph.
Cheers,
Dr. A
I had similar thoughts. Speed is what keep satellites in orbit. This example would only work in a "flat earth" scenario. The momentum adds to its centrifugal force. My argument may revolve around the premise and that example is not an accurate example of firing a bullet on Earth. IF speed can keep a satellite in orbit it's going to effect a bullet too, even if it's hard to measure, there will be a difference. Thoughts welcomed :)
Bullets that are rotating (spindrift). There is a small additional displacement downward and to the right. Need to add Ysd (vertical) to your equation. It is a small amount, but should be at least mentioned.
what if both are straight down?
Shot bullet hits first since it has a high initial velocity and dropped bullet has zero initial velocity.
Cheers,
Dr. A
It's about gravity and has nothing to do whith horizontal speed. 2 identical object are affected identcally by gravity. They both hit the ground in the same milisecond, even if one was projected hundreds of meters/feet away horizontaly.
The bullet that's been fired will reach the ground 1st regardless of the calibre of the gun, because it'll have a greater force than gravity (the intertia from the firearm) acting on it in the same direction, terminal velocity which is the top speed of something falling with only gravity acting on it is only around 180mph, whereas guns can project a bullet up to 3,000mph
Does that mean that bullet 1 falls faster than bullet 2? It takes some time to travel horizontally so in order to reach the ground at the same time it needs to drop faster? Or is the drawing incorrect and the descent is in fact starting immediately?
Picture might not be the best, but no - both bullets drop at the same rate vertically so they both hit the ground at the same time (the caveat, of course, is that you have to fire the bullet PERFECTLY horizontal).
Cheers,
Dr. A
Gravity acts on both bullets in the same direction and with the same force over the same amount of time (because the release height is identical) - irrespective of the horizontal velocity. The vertical component is not affected by horizontal movement.
Dose this equation include temperature, crosswinds and aerodynamics of the trajectory
Fernando Martinez no
or if one is not parallel, but 45 degrees for example?
Judah,
Then of course the bullet shot upwards at 45˚ would be in the air longer. Not too difficult to calculate how long it would be in the air. See, for example: ua-cam.com/video/ZPaRFr_3g2k/v-deo.html
Cheers,
Dr. A
If you fought in Fallujah, this is all irrelevant. Have you tested it as it seems as though you are an expert in ballistics
Wrextoration,
I'm a peace lover by trade. Not sure why we have such morbid examples in physics.
Thanks for the comment, and keep up with the physics!
You might also like my new website: www.universityphysics.education
Cheers,
Dr. A
Is he writing bsckwards?
Nope. Secrets here: www.learning.glass
Cheers,
Dr. A
This is so wrong it's hard to even know where to start. Because you are ignoring basic ballistic science & the basic physics behind it.
Yes all bullets and cartridges are not created equal, the ballistic coefficient makes a big difference on how long and how flat the bullet will travel along with the velocity; for instance a 6.5- 300 Weatherby with 140 grain bullet is going to go a lot further then the 30/30 and stay in the air a lot longer. When he said if "you shoot a bullet a long ways, like the distance of a football field!" A football field is not a long ways to fire a bullet, maybe a musket. This might be correct if you are shooting round musket balls not. 140 grain 6.5 mm with a balistic coefficient of 650.
I had this coversation with a friend of mine last week who was convinced that the bullet fired from the gun at a 90 degree angle would reach the ground at the same time as the bullet dropped from the same height at 180 degrees...but...it...doesn't
(Once the bullet that's been fired loses all inertian and begins to fall with nothing acting on it but gravity, that's when it will meet the ground at the same time as the one dropped)
I was explaining to him that according to chaos theory there were too many variables in 1. The angle of firing horizontally 2. Calibre of the gun which affects the speed and range of the bullet fired 3. The type of ammunition used as match-grade ammunition can be used to permit a far greater range 4. Wind resistance on the fired bullet compared to the one dropped, for this to be an accurate claim
What I did was draw the exact same diagram you have, only I pointed out the exact moments that were mathmatically sound (the full motion of the bullet being dropped and the falling motion of the bullet fired once it's lost all intertia and has only the superior force of gravity acting on it till it reaches the ground)
It's NOT true or mathmatically sound that a bullet fired horizontally will reach the ground at the same time as one dropped from the same height, because of the different ranges and speeds of different calibre firearms along with the inevitable difference in air pressure and resistance between the area you're dropping one and the area the fired one is in once it begins to fall
Gosh... I hope nobody takes what you wrote seriously. As soon as a bullet leaves the barrel, it is falling. A bullet has no "lift"... a bullet appears to travel in a decreasing radius arc that leads people to believe that it's not falling at first, but it is. That decreasing radius is due to the decreasing speed... but the rate of fall for the bullet is the same.
your mistaken and wind does not count for the purpose of the thought experiement of course. it could be done in a vaccum. The bullet fired from the gun hits last because the earth is curving away and dropping below the bullet. It passes through the straight plane drawn at the same time but it hits the GROUND last.
This guy must be a flat earther. He ignores that the earth is curved. Yes, both fall at the same rate but the bullet that has been fired has further to fall.
You got it, total flathead.
Cheers,
Dr. A
Approximate damn it
Is this done with the assumption that there is no air resistance? :>
Sandra Melodie Navarro,
Yes.
Thanks for the comment, and keep up with the physics!
You might also like my new website: www.universityphysics.education
Cheers,
Dr. A
Wouldn't air resistance come into play here? When the bullet is fired, air hits the front of the bullet and the bullet remains in the same orientation; However, when the bullet is dropped, it will not maintain the same orientation and air will hit the underside of the bullet which has a greater surface area or it may even tumble which means greater air resistance resulting in a longer fall time. They would only hit the ground at the same time if they were in a vacuum. There is also the delay in the time it takes for the bullet to leave the inside of the barrel when it isn't falling, as well as the time it takes for the firing pin to strike the primer once the trigger is pulled.
He's says as soon as it leaves the gun... He isn't calculating time in barrel, primer, time thinking about shooting, loading the gun, or time waiting for background check.
it goes without saying those factors are not to be considered in the thought experiment.
You said which will hit the ground first? The dropped bullet will hit the ground first. Obviously figure the earth is a perfect smooth sphere and discount air or wind such as even in a vaccum. You drew a straight plane. Both bullets would pass through that plane at the same time assuming the fired bullet did not hit a plane.
However the earth is round and the one fired from the gun the earth is curving downward away from it same as orbit concept and the old drawing of a cannon on a mountaintop that shoots cannon ball at 18 thousand miles per hour and of course it never hits.
Thus the rifle bullet hits LAST. so for the sake of the experiment it has to be tweaked for the class to discount the curvature of the earth and instead say "which bullet will pass through this flat plane first?" not "hit the ground".
but I understand the purpose of the thought experiment so I will let this one slide. so a person could make thousands of dollars on this bet over a lifetime. Your welcome in advance. I could ask it to Albert Einstein with thousand dollar bet and he would say "this dosent count! you tricked me! you know what I meant"!!
Excellent points, thanks very much.
Cheers,
Dr. A
Huh?
This is really easy to prove incorrect if you use an arrow or bolt out of a crossbow instead of a bullet.
I understand. Plz
thợ săn xó bêp,
Thanks for the comment, and keep up with the physics!
You might also like my new website: www.universityphysics.education
Cheers,
Dr. A
Professor I don't know when u got ur degree but the horizontal one is faster
Universities these days 😔
That's good
totaly wrong in real life
LOL @ the zero comment
Thanks for watching.
Cheers,
Dr. A
NO THEY DON"T !
MRMAX yes they do. Every time
How?
What about velocity? What about using math with numbers instead of bullshit equations . Numbers i can do on my calculator. Which cant lie to me
I like to keep the variables until the end because then you can check units. This is a good way to see if you've made a mistake.
Cheers,
Dr. A
Depending on the caliber and firearm, you can set horizontal initial velocity to 800m/s (~2600 feet/s), which would be fairly typical for a .308win rifle with a heavier bullet (175gr, or 11 grams).
Vertical initial velocity is 0, and both bullets accelerate towards the ground at approximately 9.81m/s²
Thanks for the data.
Cheers,
Dr. A