Question

Kevin and Alice are fighting over a door. Looking from the top, Kevin is applying a force of 2 N perpendicular to the direction of the door, CCW at exactly where the knob is, which is located one meter from the hinge, while Alice is applying a force of 2.5 N perpendicular to the plane of the door, CW at a point which is located half the distance from the hinge and the knob. Which direction will the door rotate?

Answer 1

Given,

Force applied by Kevin,

Force applied by Alice,

Let the distance between hinge and knob be

Torque applied by Kevin, in counter clockwise direction

Torque applied by Alice, in clockwise direction

Since torque applied by Kevin is greater, hence the door will move in counter clockwise direction.