Question

Would a door open if a force is applied on its hinges?

Answer 1

Explanation:

1. Torque is the product of force and perpendicular distance from the pivot, i.e., $\mathrm{Torque}=\mathrm{Force}\times \mathrm{Perpendicular}\mathrm{distance}$.
2. So we need maximum torque for easy opening or shutting a door by applying minimum force.
3. When the force is applied at the hinges, the line of action of the force passing through the axis of rotation is zero.
4. Thus the force is maximum and torque is minimum near the hinge.
5. Hence, there will be no turning effect however large force is applied.