Question

A body weighs $50N$ in air and it weighs $40N$ when immersed in water. Find out the force of buoyancy acting on the body in water.

• A. $10N$, upward direction
• B. $90N$, upward direction
• C. $10N$, downward direction
• D. $90N$, downward direction

Answer 1

The correct option is A $10N$, upward direction

Given:
Weight of body in air ($w_1$) $=50N$
Weight of body when immersed in water ($w_2$) $=40N$

We know that, buoyant force ($F_B$) always acts on the body in the upward direction, and the value of buoyant force is equal to loss in weight of the immersed body in water ($w$).
$\therefore w=F_B=w_1-w_2$
$\Rightarrow F_B=50-40$
$\Rightarrow F_B=10N$