Question

Choose the scenarios below in which non-zero total work is done. [Select all options that apply by entering a string of letters. For example: If you believe X, Y, and Z are true, then enter 'XYZ'.]

A) You get really tired from pushing against a sturdy wall.
B) You push a box from one side of the room to the other.
C) You lift a weight up and hold it over your head.
D) You lift a weight up off of the ground, and then put it back down again.

Answer 1

Non-zero total work is done in scenarios B (pushing a box across a room) and D (lifting a weight up and then down), because in both cases there is displacement in the direction of the applied force.

Step-by-step explanation:

In physics, the scenario where non-zero total work is done involves both a force being applied and displacement in the direction of that force. For work to occur, there has to be movement in the direction the force is applied, and the force must not be zero.

• B) You push a box from one side of the room to the other. - This is an example of work because the box is displaced while force is applied to move it across the room.
• D) You lift a weight up off of the ground, and then put it back down again. - Lifting an object off the ground and putting it down involves displacement in the direction of the force (upward and downward), which means work is performed against the gravitational force.

Scenarios A and C are not examples of work done. In A, even though one may feel tired, there is no displacement when pushing against a wall. In C, holding a weight in the air involves no displacement since the weight is stationary, despite the force applied to support it against gravity.