Solve the all given parts of following question:
Question: A 20 kg cart is at rest when begins to push the cart. The cart accelerates for 5 s and a person then the person stops pushing. Ten seconds later and 12 meters from the point at which the person stopped pushing, the cart comes to rest.
Part A: What was the velocity at the end of the first 5 s?
Part B: What is the magnitude of the friction force on the cart?
Part C: What force did the person apply during the first 5 s?
I need help to determine the magnitude of the friction force on the cart.