PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A classroom door is hinged at one side. A student applies a force perpendicular to the plane of the door to open it.
(i) Define (a) the moment of a force (torque) about an axis and (b) the lever arm.
(ii) Explain qualitatively why the same force opens the door more easily when it is applied at the handle than when it is applied halfway between the handle and the hinges.
(iii) If the student continues to apply the same force but shifts the point of application to a position that is one-third of the original distance from the hinges, describe how the turning effect produced on the door will change.