Use the figure to answer the 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.
-What is the force needed to move the mass at a constant speed?
A)0
B) mg
C)mg
D)2mg
E)4mg

Question

Use the figure to answer the 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. 
-What is the force needed to move the mass at a constant speed?
A)0 
B) mg 
C)mg 
D)2mg 
E)4mg

Quizplus · Accepted Answer

According to Newton's second law of motion, force equals mass times acceleration (F=ma). In this case, since the mass is moving at a constant speed, its acceleration is zero. Therefore, the net force acting on the mass must also be zero. This means that the force applied to the rope (F) must be equal in magnitude and opposite in direction to the force of gravity acting on the mass (mg). Therefore, the force needed to move the mass at a constant speed is F = mg.

Use the Figure to Answer the Question