Question

Give an experiment to verify the principle of moments.

Answer 1

Verification of Principle of Moments:
Suspend a metre scale horizontally its midpoint O’, by means of a thread with its other end connected to a fixed support.
Now suspend some weights on both sides of the mid-point and adjust their distances in such a way that scale again becomes horizontal.

Let W₁, W_2, and W₃, W₄ be the weights suspended and l₁, l_2, and l₃, l₄ are respective lengths.
The weights W₁ and W₂ tend to turn the scale clockwise while the weights W₃ and W₄ tend to turn the scale anti-clockwise.
Total clockwise moments = W₁ × l₁ + W₂ × l₂
Total anti-clockwise moments = W₃ × l₃ + W₄ × l₄
In equilibrium, when the scale is horizontal, it is found that:
Total clockwise moments = Total anti-clockwise moments
W₁l₁ + W₂l₂ = W₃l₃ + W₄l₄
This verifies the principle of moments.