Question

A body floats in a liquid contained in a beaker. The whole system as shown falls freely under gravity. The upthrust on the body due to the liquid is

• A. Zero
• B. Equal to the weight of the liquid displaced
• C. Equal to the weight of the body in air
• D. Equal to the weight of the immersed position of the body

Answer 1

The correct option is A Zero

Upthrust is net weight of liquid displaced
Upthrust $=\rho V_{liquid}(g-a)$
where $a=$ downward accleration and
$V=$ volume of liquid displaced
But for free fall, $a=g\Rightarrow \text{Upthrust}=0$