Question

In a physical balance working on the principle of moments, when $5\text{mg}$ weight is placed on the left pan, the beam becomes horizontal. Both the empty pans of the balance are of equal mass. Which of the following statements is correct?

• A. Left arm is longer than the right arm
• B. Left arm is shorter than the right arm
• C. Every object that is weighed using this balance appears lighter than its actual weight.
• D. Both the arms are of same length

Answer 1

The correct option is B Left arm is shorter than the right arm

According to principle of moments when a system is stable or balance, the anti-clockwise moment is equal to
clockwise moment.
i.e., load $\times$ load arm $=$ effort $\times$ effort arm
When $5\text{mg}$ weight is placed, load arm shifts to left side,
hence left arm becomes shorter than right arm.
Hence, option $\left(C\right)$ is correct.