A light rope runs through two frictionless pulleys of negligible mass. A mass, m, is hung from one of the pulleys and a force, F, is applied to one end of the rope so that the mass moves at a constant speed. If the force is applied over a distance, d, the distance the mass moves is
A) 0
B) d
C) d
D) d
E) 2d

Question

A light rope runs through two frictionless pulleys of negligible mass. A mass, m, is hung from one of the pulleys and a force, F, is applied to one end of the rope so that the mass moves at a constant speed. If the force is applied over a distance, d, the distance the mass moves is
A) 0 
B) d 
C) d 
D) d 
E) 2d

Quizplus · Accepted Answer

Since the mass moves at a constant speed, the tension in the rope must be constant throughout the system. Therefore, the distance the mass moves must be equal to the distance the end of the rope moves, which is the distance over which the force is applied, d.

A Light Rope Runs Through Two Frictionless Pulleys of Negligible