(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

There is a 2450 kg car being pushed by a group of students. The car is pushed a distance of 12 m in 8.95 seconds. The coefficient of friction is .450.

a) What is the net work being done?

b) Work done by street?

c) Work done by students?

2. Relevant equations

Wnet=Kf-K0

Wf=-Ff*d

d=[(v0+vf)t]/2

KE=[mv^2]/2

3. The attempt at a solution

For a, Wnet=Kf-K0, and K0=0.

To find Kf, I started to find Vf, using the displacement formula

12=[vf*8.95]/2

vf=2.68 sec.

Then I found Kf

Kf=[2450*2.68^2]/2

Since K0=0, Wnet=8798 J (same value as Kf+0)

b asks for work done by street so I assumed that meant Wf.

At this point, I wasn't sure how to find Ff to use in Wf=-Ff*d formula

I thought Ff=μ*Fn

Is Fn=m*g? Or do I multiply m*a, after finding out acceleration?

Since I found Vf in the last step, do I divide that by time to find acceleration?

c is work done by students, which is Wpush/applied force.

Wnet=Wpull-Wf

Do I add Wf to Wnet to find applied force?

At this point, I don't really know what I'm doing.

Can someone give me a few tips on the concepts that should be understood about this problem and explain whatever errors I'm making?

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# Homework Help: Finding Work with friction

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