Question

Hello everyone, i have a question about challenge problem 7 from 2-D Kinematics. Why can't we choose our 'x'-axis along the hill and have x(t) = vcos(theta + phi)t + sin(phi)gt^2 where the second term is the acceleration component from gravity. We set up similar equation for the new 'y' axis and solve for time T such that y(T) = 0, and then plug into the x(t) equation. This should be the same correct?

Answer 1

Howdy! Unfortunately, it seems you have not attached a visual of the problem you are referring to. Therefore, I can't piece together what you are asking. Is it possible to attach a file?

Answer 2

Done. Its problem 7

Answer 3

I believe I follow the logic so far, I understand where most of your x-equation is coming from and it looks relatively sound. Just for extra clarification, could you type the "similar equation for y"?

P.S. As I stated above, so far the logic seems sound, yet I caution you that this method isn't delineated/taught b/c it jumbles together the components a bit much. It's akin to not showing your work in a sense by not solving it in a systematic approach such as, well, systems of equations. And by that I mean, one where the variables phi and theta are dealt with separately, then substituted for - just as x and y are.

Answer 4

I think the y equation would be:
y(t) = vsin(theta + phi)t - cos(phi)gt^2

Its just my background is in mathematics, so its more natural for me to rotate coordinates

Answer 5

Hello, and A Warm Welcome to Open Study!