The diagrams show, not to scale, three different situations in which a force F acts. Also shown in each case is a distance d.
Diagram 1:
Person sitting on a chair
Diagram 2:
Wheelbarrow being lifted
Diagram 3:
Weight being lifted by a motor
Which line in the table shows whether or not work is being done by force F in each situation and, if so, whether the work done is equal to F x d?

Answer:

11) D

Work is only done when a force is applied and a body moves for a distance in the direction of the force.

Diagram 1
The person is siting on a chair. There is a force (weight) but there is NO movement in any body (person nor chair). So the force is not doing any work. Therefore, diagram 1 would not be in any column.

Diagram 2
The wheelbarrow is being lifted upwards in the direction of the force. So work is being done by the force ‘F’. However, the distance (d) labelled on the diagram is not the distance moved by the force. The distance labelled is perpendicular to the direction of the force. Hence, work done = F x d, does not apply to this diagram.
Diagram 2 will be in the first column but not in the second column.

Diagram 3
The pulley is pulling the weight upwards by applying force’F. The weight moves by the distance ‘d’ as the distance labelled is in the direction of the force. Hence, the formula work done = F x d, is applicable in this case.
Diagram 3 would be in the first and second column.

The correct answer is D.