The 1 560 kg solid steel door to a bank vault is 2.00 m high, 1.00 m wide and 10 cm thick. One hinge is 60.0 cm down from the top on the left hand side of the door. The other hinge is 30.0 cm up from the bottom. What horizontal force, in what direction, does the door exert on the upper hinge?
A) 6 950 N, left
B) 6 950 N, right
C) 7 640 N, left
D) 7 640 N, right
E) 15 300 N, left

Question

Quizplus · Accepted Answer

The force exerted by the door on the upper hinge is to the right, due to the torque created by the weight of the door acting at its center of mass. The force can be calculated by considering the torques about the lower hinge to find the force at the upper hinge that keeps the door in equilibrium.

The 1 560 Kg Solid Steel Door to a Bank