# Tired superman

**Classical Mechanics**Level 3

One fateful day, a car with weight \(5000~\mbox{N}\) has malfunctioned on the entry ramp to a highway. It is now sliding down the ramp, angled at \(30^\circ\) with respect to the horizontal. The coefficients (static and kinetic) of friction are \(0.4\). Then, Superman comes and saves the day! However, he just had a fight with the bad guys so he wants to use the least amount of force as possible. First, he uses the minimum amount of force to stop the car. Then, he uses the minimum amount of force to push the car so it starts sliding slightly upward along the ramp. What is the absolute value of the difference between the two forces he uses **in Newtons**?

**Details and assumptions**

- Answer to the nearest integer.
- Assume the force is directed along the ramp.
- Submitted by Christopher B.

**Your answer seems reasonable.**Find out if you're right!

**That seems reasonable.**Find out if you're right!

Already have an account? Log in here.