# Homework Help: Crate sliding down a ramp

1. Feb 27, 2014

### hanzlikm

"A 4.00-kg crate slides down a ramp. The ramp is 1.80 m in length and inclined at an angle of 28.0° as shown in the figure. The crate starts from rest at the top, experiences a constant friction force of magnitude 4.50 N, and continues to move a short distance on the horizontal floor after it leaves the ramp.
https://www.webassign.net/serpse8/8-figure-10-alt.gif (figure)
(A) Use energy methods to determine the speed of the crate at the bottom of the ramp.

(B) How far does the crate slide on the horizontal floor if it continues to experience a friction force of magnitude 4.50 N?"

so i solved part A for the speed of the crate at the bottom of the ramp and got 3.54m/s.

Using the speed, i then solved part B for the distance it traveled on the floor and got 5.57m using 1/2*mv2 = ffd
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Then the problem asks, what will be the final speed at the bottom of the ramp if it has an initial speed of .6m/s?

and this is where I get stuck, im not sure how to calculate that into the equation.

Thanks in advanced for the help.

Last edited: Feb 27, 2014
2. Feb 27, 2014

Welcome to PF
Where's the figure?

3. Feb 27, 2014

### hanzlikm

thanks, Just updated the thread with the figure hopefully it works for you.

4. Feb 27, 2014

### PhanthomJay

I didn't check your numbers, but with an initial velocity, the crate has initial kinetic energy. So use the same energy equation, and include the initial KE when calculating the kinetic energy change.

5. Feb 28, 2014

### hanzlikm

woww that totally worked, thanks a lot!