# Sliding and rolling friction

1. Aug 25, 2010

### reinrain

help please I don't know what to do with this problem can someone please tell me how to solve the following problems, i need to know how to solve and get the right answers not just get the right answers.

A force of 1000N is applied to a 1200kg car if the coefficient of the rolling friction is 0.04 what is the cars acceleration?

An 80 lb wooden crate rests on a horizontal floor. if the coefficient of static force is 0.5 how much force is needed to set the crate in motion?

please help!!! i need the step by step solution so i will be able to solve the future problems....thank you

2. Aug 25, 2010

### rock.freak667

Hi reinrain,

At PF, we can't just give you the full solution, but we can certainly help you arrive at it.

Start by drawing a free body diagram and put all of the forces on the car.

How does the frictional force relate to the normal force?

Can you formulate an expression for the resultant force on the car using Newton's 2nd Law?