Question

A spring balance reads W₁ when a ball is suspended from it. A weighing machine reads W₂ when a tank of liquid is kept on it. When the ball is immersed in the liquid, the spring balance reads W₃ and the weighing machine reads W₄.

(a) W₁ > W₃ 

(b) W₁ < W₃ 

(c) W₂ < W₄ 

(d) W₂ > W₄

Answer 1

Correct Answer is: (a) W₁ > W₃, (c) W₂ < W₄

W₁, W₃ are the forces exerted by the ball and the spring balance on each other before and after immersion.

W₂, W₄ are the forces exerted by the tank and the weighing machine on each other before and after immersion.

Let m and M be the masses of the ball and the tank respectively, and let N be the force of interaction between the ball and the liquid in the tank.

W₁ = mg W₂ = Mg

W₃ + N = mg

W₄ = N + Mg