Question

A beam balance is shown in the figure. In order to balance the known mass of 9 gm, an equal mass of 9 gm should be kept on the other side to balance the beam. If 5 gm of mass is kept on the other side of the scale, how much more mass is needed to balance?

• A. 9 gm
• B. 5 gm
• C. 4 gm
• D. 2 gm

Answer 1

The correct option is C 4 gm

Let the unknown mass be x. In order to balance the known mass of 9 gm, the equal mass of 9 gm is required. Thus, x gm + 5 gm = 9 gm; x = 9 gm – 5 gm = 4 gm. So 4 gm more is required to balance the two arm of the beam balance.