PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
Two identical wooden doors, each 0.90m wide, are hinged on their left edges. A horizontal push of 40N is applied on each door.
Door A is pushed at the outer edge, exactly perpendicular to the door surface.
Door B is pushed at a point 0.45m from the hinge, making an angle of 45∘ with the plane of the door and directed outward.
Answer the following sub-parts, giving clear reasoning in each case.
(i) Define the term "torque" about a given axis.
(ii) Without performing any numerical calculation, state which door experiences the larger turning effect. Justify your answer qualitatively with reference to the factors on which torque depends.
(iii) Explain, with reasons, which door will open more easily under the given pushes.
(iv) If the objective is to minimise the effort required to open a door, list two practical design changes that could be made, based on your discussion above.