Question

how can the moment of force be zero when the force is itself is not zero. give example.

Answer 1

If the force is not zero, moment of force is zero when the perpendicular distance of line of action of force from the point of pivot is zero.....because
Moment of force = Force x Perp. dist.

For example, if you want to open a door by applying force at its hinge(minimum distance from the point of pivot) , howsoever large force you apply, you cannot open the door, I.e., moment of force will be zero.

Answer 2

Answer:

When the perpendicular distance is zero the moment of force is zero because torque= either force*perpendicular distance .

For example, if force is 2N and perpendicular distance is 0 m then torque =2*0 =0 Nm

Explanation:

Example

if the knob of the door is near it's hinge and distance is 0 the force will be more to open the door .