Question

A uniform metre scale is kept in equilibrium. It is supported at the 60 cm mark and a mass M is suspended from the 90 cm mark as shown in the figure. What is the relation between the weight of the scale and the weight of mass M?

• A. The weight of the scale is greater than that of the weight of mass M.
• B. The weight of the scale is lesser than that of the weight of mass M.
• C. The weight of the scale is equal to than that of the weight of mass M.
• D. The weight of the mass is zero.

Answer 1

The correct option is A

The weight of the scale is greater than that of the weight of mass M.

Let M be the load and W be the weight of the scale.
Then load arm = 90 - 60 = 30 cm
Effort arm = 60 - 50 = 10 cm
In equilibrium:
Load $\times$ Load arm = Effort $\times$ Effort arm
or M $\times$ 30 = W $\times$ 10 $\Rightarrow$ W = 3 M
Hence, the weight of the scale is greater than that of the weight of mass M.