Short answerModerate1 mark
A stone is tied to a string and displaced from A to B by application of constant force F in three different ways as shown in the diagram below. Arrange the three cases in ascending order of the work done by the force. (Given AJB is a semi-circle, θ < 90° and AB = 20 m)
Topic: Work done by a force
Question wording verified against source paper
Answer
Exam answer
Case 1 < Case 3 < Case 2.
Explanation
W = Fs cos θ. In Case 1 the force is perpendicular to the instantaneous displacement, so W = 0. In Case 3, 0° < θ < 90°, and in Case 2 θ = 0°, giving maximum work.
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