Question

A uniform meter rule of weight $ 10gf $ is pivoted at its $ 0 $ mark. What moment force depresses the rule?
(A) $ 5gf\,cm $
(B) $ 10gf\,cm $
(C) $ 100gf\,cm $
(D) $ 500gf\,cm $

Answer 1

Hint: Torque or moment of force is the tendency of force to rotate an object about an axis, fulcrum, or pivot.
Just as a force is a push or a pull, a torque can be thought of as a twist to an object.

Complete step by step answer:
The direction of the force is important because the resulting motion of the object is in the same direction as the force. The product of the force and the perpendicular distance to the center of gravity for an unconfined object, or to the pivot for a confined object, is M called the torque or the moment.
As we have a $ 10gf $ weight at $ 0 $ mark and it will have a perpendicular distance of $ 50cm $ from point $ O $ that is from the center of the scale we will have moment of force $ = 50 \times 10gfcm = 500gfcm $ .
Hence it will have 500gfcm to depress the rule.

So, the correct answer is “Option D”.

Additional Information:
The turning effect of a force is known as the moment. It is the product of force multiplied by the perpendicular distance from the line of action of the force to the pivot or point where the object will turn. SI unit of moment of force is Newton-meter (Nm).

Note:
In physics, they signify the same thing but in mechanics, they tell slightly different meanings.
Both have the same unit i.e. N-m but torque is a movement force whereas the moment is a static force.
Torque is used where there is rotation involved whereas moment is used where there is no rotation.