Physics Homework Question

Question

A mover is trying to lift a piano (slowly) up to a second-story apartment . He use a pulley and ropes to decrease the force needed to raise a heavy load

 

But for every meter the load is raised, how much rope must be pulled up? Account for this, using energy concepts.

But for every meter the load is raised, how much rope must be pulled up? Account for this, using energy concepts.

	For each meter of the load is raised, 0.5 m of rope must be pulled up.
	For each meter of the load is raised, 1.5 m of rope must be pulled up.
	For each meter of the load is raised, 2.5 m of rope must be pulled up.
	For each meter of the load is raised, 2 m of rope must be pulled up.

all of those choices are in meters 

Answer 1

Assuming that there are no dissipative forces act over the rope.

The load is hung from the pulley block and the effort is used to pull upwards on the free end of the rope. Because the load is now hung from two ropes, each taking half of the strain, the effort needed is only half the size of the load.

Hence to move the load for every meter, two meters of rope must be pulled up.

Option (d) is the right choice.