Question

The weight of a metal block in air is $200N$. The block is then dipped in water and weighed again. If the weighing scale now reads $150N$, what is the weight of displaced water?

• A. $200N$
• B. $150N$
• C. $350N$
• D. $50N$

Answer 1

The correct option is D $50N$

Given:
Weight of the block, $W=200N$
Reading of the weighing scale, $w^{\prime }=150$
This loss in weight is due to buoyant force exerted by water in upward direction.
Upward buoyant force, $F=(W-w^{\prime })N$
$=(200-150)N=50N$
According to Archimedes’ principle, the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces.
Hence, weight of the displaced water$=F=50N$.