Verifying The Principle of Moments

(d) Describe how to verify the principle of moments.

We have already covered the principle of moments in the previous post, as well as the principle of moments for a body in equilibrium

To verify the principle of moments, we can use the following experiment.


First of all, we will balance a meter scale on its 50cm mark. Then on the 70 cm mark of the rule, we will put three weights of 4,6 and 10 N respectively.

Now we will calculate the moment due to these three weights. We know that the distance from the pivot is 20 cm. We will first convert it to meters, that is 0.2 m. Now, the moments of these forces will be (4 * 0.2) + (6 * 0.2) + ( 10 * 0.2) which equals to 4 Nm

Now, we will use a weight which is equal to the sum of the previous three weights, that is a weight of 20 N. We will put this weight at the 30 cm mark of the rule, that is the same distance of 20 cm from the pivot, but this time on the other side of the pivot to balance the scale.

The moment produced by this weight 20 * 0.2 = 4 Nm. If the meter rule is uniform, it would balance, therefore verifying the principle of moments, which states that the moments produced due to several forces applied at a single point, are equal to the moment produced by the sum of those forces.