4.7 of text:
A 68.5 kg skater moving initially at 2.40 m/s on rough horizontal ice comes to rest uniformly
(with constant acceleration) in 3.52 s due to friction from the ice. What force does friction exert
on the skater?
Hint: First, model the skater as slowing down with a constant acceleration. Second, given the
stopping time find what that acceleration is. Then, use that acceleration to find the net force
from Newton's second law.
Fig: 1