A block of mass m is initially held in place on the left side of a track at a di
ID: 1288104 • Letter: A
Question
A block of mass m is initially held in place on the left side of a track at a distance h above the
bottom of the track. The track is completely frictionless, with the exception of a rough
horizontal section of track of length h which has a coefficient of kinetic friction
mu = 0.11. If the block is released from rest, how many times does the block completely cross the
rough section of track before it stops?
Explanation / Answer
m*g*h = n * 0.11*mg*h
energy conservation
potetntial energy = n * energy against friction
so we get
n = 1/0.11 = 9.09
completly cross means n = 9