I was hoping I could get some help on this particular exam review question:(adsbygoogle = window.adsbygoogle || []).push({});

[4] A 3.0kg crate slides down a ramp at a loading dock. The ramp is 1.0m in length and inclined at an angle of 30 degrees. The crate starts from rest at the top of the ramp and experiences a constant frictional force of magnitude 5N, and continues to move for a short distance on the flat floor. (a) Use the energy methods to determine the speed of the crate when it reaches the bottom of the ramp. (b) Determine the acceleration of the crate.

For part A, I found the initial Potential Energy to be 14.75 (PE=mgh), and since PI-initial is 14.75 and KE-initial is 0, KE-final must be 14.75 as well (since PE-final will be 0). I then used KE=(1/2)mv^2 to find the velocity, which I found to be 3.1 m/s.

For part B, I used W=F*d to find Work to be 5J (F=5, d=1). I then used W=m*a*d to find the acceleration, which I think I did incorrectly. Using that formula I found the acceleration to be a=1.667 m/s^2.

I don't think these are correct, but I cannot think of a way to better include the frictional force of 5N. Any suggestions?

Thanks for your time.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Energy and a Frictional Incline

**Physics Forums | Science Articles, Homework Help, Discussion**