Question

An elevator supported by a single cable descends a shaft at a constant speed. The only forces acting on the elevator are the tension in the cable and the gravity. Which one of the following statements is correct?

Group of answer choices

The gravitational force does negative work.

The tension force does positive work.

The work done by the gravity is zero joules.

The work done by the tension force is zero joules.

The net work done by the two forces is zero joules.

Answer 1

The correct statement among the options provided is: The net work done by the two forces is zero joules.

When an elevator supported by a single cable descends at a constant speed, the forces acting on the elevator are the tension in the cable and the force of gravity. Both of these forces are in opposite directions but have equal magnitudes. Since the elevator is moving at a constant speed, there is no change in its kinetic energy. Therefore, the net work done on the elevator by these forces is zero joules, as the work done by gravity (which is negative) is balanced by the work done by the tension force (which is positive).