# Homework Help: Finding Minimum Work?

1. Feb 22, 2010

### coffeecake

1. The problem statement, all variables and given/known data

What is the minimum work needed to push a 1770 kg car 346 m up a 16.2 deg incline?
Without friction, I got the the answer of 1670000 J.

What is the minimum work needed if the coefficient of friction is 0.25?

2. Relevant equations

3. The attempt at a solution

Ff=µFN

FN = 17346 cos 16.2
FN = 16657 N
Ff = .25 * 16657 = 4164.25 N

then, sin16.2 * 17346 = 4839 N

add them? subtract? or is it all completely wrong?

Last edited: Feb 22, 2010
2. Feb 22, 2010

### collinsmark

Hello coffeecake,

Try to at least give us your best effort on describing how you've thought through what the steps might be. We're not supposed to offer help unless you've shown that you've given the problem some effort. Things that might be useful in your response: What's the nature dynamic friction? How do you calculate the forces involved in dynamic friction. Can you think of any equations that relate force and work (force and energy)?