Fully agree. By trigonometry you know that TAN 30º = Y / X Plug in the equations that you found before TAN 30º = 4.9 t^2 / 20 t cancel out one of the 't' and divide by 20, then solve for t t = TAN 30º / 0.245 t = 2.3565
I did it by another method where you simply use the 30-60-90 triangle , letting y to be x , and x to be xsqrt of 3 , and substitute to solve for x , then the d will be 2x since its opposite to degree 90 ..
I had a problem very similar to this in my book, and I couldn't understand the solution provided. I'm very grateful for your explanation as I was able to understand it now.
Thank you so much for this totally beneficial Phy series sir. I think we can solve the question easier by taking Y0 as d*sin(30) and Yfinal as 0 but exactly in physics there are lots of different methods to solve one specific question :).
I made equations for x and y like you did. Then did tan 30 = y/x. Then subbed in the y and x equations into the tan 30 ration then solved for t. Then used pythagorus once i got the magnitudes of x and y
When using the X formula, why don't you use the formula for the x component (vsinx) instead but use the actual initial velocity (20 m/s) to solve for t?
Could someone explain how to solve this using a 30-60-90 triangle methodolog? That is the method that makes the most sense to me, yet im having trouble applying it in this scenario
good day I was wondering why for time in the air for x , I was under the impression that is should be vsintheta = 10 ? and not just the whole initial velocity. king regards Your Student
I am wondering why not set the world (x and y coordinates) perpendicular to the slope (d), so x axis would be perpendicular, y would be equal/paralel to the d slope. This way the projectile initial velocity would be 30 degrees instead of 0, but we don't need to bother Pythagoras.
Vida, Coordinate transformations are implemented in many situations. There is no wrong or right way of doing a problem (as long as you don't violate a math or physics rule). Use whatever method makes it easier for you.
okk i get it now. so i can take any number and it won't effect the result. thank you very much sir for your quick response and for your great videos :)
Hi prof. Why don't you use pythagoras" theorum to calculate the hypotenuse? we do assume that this is a right triangle, right? i calculated the length of X and Y. i used those answers to calculate the hypotenuse.
You didn't include the units when you wrote 6.5. Can you give the comparison? (your result and the result in the video?) 6.5 seems like a large error that would not come from a rounding error.
There are often different ways in which you can solve a problem. What I like to teach is to start from the basic principles and develop the equations, rather than to grab one that works in one situation and then wonder of it works for another situation.
The delta symbol is used to denote a "change" of a "difference", where a difference is the same thing as a subtraction. In order to find the slope we must pick two points on the slope and calculate the "rise' and the "run".
The best projectile problem ever.
It's way easier to use tan30° and solve for t
Fully agree.
By trigonometry you know that
TAN 30º = Y / X
Plug in the equations that you found before
TAN 30º = 4.9 t^2 / 20 t
cancel out one of the 't' and divide by 20, then solve for t
t = TAN 30º / 0.245
t = 2.3565
@@na-sx7ji actually, it's even more easier if you use, tan330, you will not get your signs wrong
I did it by another method where you simply use the 30-60-90 triangle , letting y to be x , and x to be xsqrt of 3 , and substitute to solve for x , then the d will be 2x since its opposite to degree 90 ..
That works! Good technique.
because of the angle is 30 degrees that will result to x and y direction to be unequal ....lovely ,fasinating thank u sir
Yes, and in this case we need to find the x-y relationship using the linear equation: y = mx + b
I had a problem very similar to this in my book, and I couldn't understand the solution provided. I'm very grateful for your explanation as I was able to understand it now.
Great! Glad you found our videos. 🙂
Wow! I wish I had learned to solve physics problems like this from the start! 😢 Thanx! 😊
Learning these fundamental methods gives one a good foundation indeed.
Thank you so much for this totally beneficial Phy series sir. I think we can solve the question easier by taking Y0 as d*sin(30) and Yfinal as 0 but exactly in physics there are lots of different methods to solve one specific question :).
Thanks and yes, there are indeed different methods to solving the same problem.
You are the best. I have exam but i did know nothing until now thank you.
I made equations for x and y like you did. Then did tan 30 = y/x. Then subbed in the y and x equations into the tan 30 ration then solved for t. Then used pythagorus once i got the magnitudes of x and y
Very good. There are usually multiple ways to solve a problem.
X=Vi*t ==> t=X/Vi
Y=1/2*g*t^2 ==> Y=1/2*g*(X/Vi)^2
X=(2Vi^2/g)*(Y/X)=(2Vi^2/g)*tan(θ)=47m
cos(θ)=X/d ==> d=X/cos(θ)=54m
When using the X formula, why don't you use the formula for the x component (vsinx) instead but use the actual initial velocity (20 m/s) to solve for t?
ya , i was wondering why, i was under the impression that is should be vsintheta = 10 ?
can I plug in both y and x at the same time on y=mx ? I did this and got t=2.34 which is pretty close so is that right?
Hi there, where did you take the 0.5 for y from ?
The sin (30) = 0.5
thank you SO much for your helpful videos!!
Could someone explain how to solve this using a 30-60-90 triangle methodolog? That is the method that makes the most sense to me, yet im having trouble applying it in this scenario
That method probably would not work on this problem, since this is not a static case but a projectile motion problem.
@@MichelvanBiezen hm I see thanks
Since the object is travel downwards it means the final position is negative y direction or?
Depends on the reference point. If the lowest point is considered y = 0, then the final height = 0.
Thank you Sir
good day
I was wondering why for time in the air for x , I was under the impression that is should be vsintheta = 10 ? and not just the whole initial velocity.
king regards
Your Student
Because to find the time in the air, only the vertical component determines the time in the air.
understood :)
comprendo
appreciated
Wonderfully explained sir 👌 thankyou
Thank you. Glad you liked it.
I am wondering why not set the world (x and y coordinates) perpendicular to the slope (d), so x axis would be perpendicular, y would be equal/paralel to the d slope.
This way the projectile initial velocity would be 30 degrees instead of 0, but we don't need to bother Pythagoras.
Vida,
Coordinate transformations are implemented in many situations. There is no wrong or right way of doing a problem (as long as you don't violate a math or physics rule). Use whatever method makes it easier for you.
why did you take hypotenuse=1 ? can you explain it please?
Since the slope is the RATIO of y/x = rise / run, it doesn't matter what you pick for the hypotenuse. One is the easiest number to work with.
okk i get it now. so i can take any number and it won't effect the result. thank you very much sir for your quick response and for your great videos :)
Thank you!!
You're welcome!
you can use sin(30) = y/x and get (t) , it's small easy
THAT WOULD BE TAN , NOT SIN. AS D IS THE HYPOTENUSE
masterly lecture! thanks
that was tough question thanks for solution
Most welcome
Hi prof. Why don't you use pythagoras" theorum to calculate the hypotenuse? we do assume that this is a right triangle, right? i calculated the length of X and Y. i used those answers to calculate the hypotenuse.
+Chad Leigh There are often multiple ways to accomplish the same thing.
You didn't include the units when you wrote 6.5. Can you give the comparison? (your result and the result in the video?) 6.5 seems like a large error that would not come from a rounding error.
Thank You for the videos
you lost me on the formula y=mx+b where is this from. thanks
y - mx + b is the general equation of a straight line.
It is used to find the relationship between x and y in the problem.
you can use the triangle rule to find the relation between x and y
Michel van Biezen tan30 = y/x
+Alaa Ayman what triangle rule, ive looked it up it doesnt come up
thank you very much
to find x and y taking tan thita will be much easier, tan30=y/x
That definitetly works. In our videos we try to show the more general methods for solving specific problems.
should the slope not be a negative value?
We can turn the coordinate system upside down, so we just concentrate on the x-y relationship,.
how can I find y value?
We are using the equation of a straight line in the form: y = mx + b
This one is easy peasy, solve the other more complicated version which has its initial velocity at an angle.
Those can be found in this playlist: PHYSICS 3.1 PROJECTILE MOTION ON AN INCLINE
@@MichelvanBiezen Thanks, I appreciate the effort you do
why we cant use the time of flight formula to find t?
Try it and see if you get the same answer.
yes it does give the same answer, by finding Vyo from 20tan30. From the flight formula, 2Vo/g = (2 X 20tan30) / 9.8.
There are often different ways in which you can solve a problem. What I like to teach is to start from the basic principles and develop the equations, rather than to grab one that works in one situation and then wonder of it works for another situation.
thanks a lot
How is it that (delta y/delta x) = (0,5/0,866) ?? The x and y value calculated is not a delta value?
Thanks to anyone who help me out here :)
The delta symbol is used to denote a "change" of a "difference", where a difference is the same thing as a subtraction. In order to find the slope we must pick two points on the slope and calculate the "rise' and the "run".
thank youu
i use tangent of theta to find the time, and i get 2.36 seconds
Riqy Rizqyandra
There are usually multiple ways to do the same problem. It looks like you found a good way.
awesome. thanks a lot. why not use -y/x=tan30. if equation about x, y is used. I think the slope is negative.
Andy,
Try it and see if you get the same answer.
The key to projectile problems often is finding the time in the air,
I did the exact same thing to solve for t, then it's just more trig to arrive at the same answer given in the video.
هذا مارح يجينا ان شاء الله بسوي سكب
👍
i dont know why my answer is 94.26m lol