Inclined plane and velocity

1. Oct 24, 2004

pulau_tiga

Inclided plane

Hi!

I have a physics question.

A block with mass m=14.7 kg slides down an inclined plane of slope angle 44.4* with a constant velocity. It is then projected up the same plane with an initial speed 2.55 m/s. How far up the incline will the block move before coming to rest?

I know that Fnet in the x-direct (assuming x-axis is parallel to the inclined). is 0 since there is no acceleration, but constant V. Therefore Fparallel + -friction = 0. Uk = tan(44.4).

On the way back up:
Fnetx = ma
Fapp + -f + -Fgx = ma
This does not work out, as I get a to = 0.

I need acceleration in order to find the distance travelled up the incline. Using

If anyone could help me out it would be greatly appreciated.
Thanks.

2. Oct 24, 2004

Staff: Mentor

As you realize, on the way down the net force is zero. Use this fact to figure out the force of friction. Hint: On the way down, friction and gravity (the component parallel to the plane) act in opposite directions; on the way up, they act in the same direction. Use this fact to find the force and then the acceleration on the way up.

Also: The kinematic equation you will need is $v_f^2 = v_i^2 + 2ad$.

Last edited: Oct 24, 2004