A rigid door 1.0 m wide is hinged along one vertical edge
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A rigid door 1.0 m wide is hinged along one vertical edge. Two forces act simultaneously on the door in the plane of the door:
• Force P of magnitude 20 N is applied at the free edge, making an angle of 60∘ with the plane of the door (directed outward away from the hinges).
• Force Q of magnitude 15 N is applied at a point 0.60 m from the hinges, perpendicular to the plane of the door and directed inward.
(i) Resolve force P into components perpendicular and parallel to the position vector from the hinge line and hence obtain the magnitude of its moment arm.
(ii) Calculate the torque produced by each force about the hinge line, clearly indicating their senses.
(iii) Determine the net torque acting on the door and state whether the door will start opening or closing.