Question

A block of volume V and of density ${\sigma }_b$ is placed in liquid of destiny ${\sigma }_1({\sigma }_1>{\sigma }_b)$, then block is moved upward upto a height h and it is still in liquid$.$ The increase in gravitational Potential energy of the block is $:$

• A. ${\sigma }_{b}vgh$
• B. $({\sigma }_b+{\sigma }_1)Vgh$
• C. $({\sigma }_b-{\sigma }_1)Vgh$
• D. none of these

Answer 1

The correct option is A ${\sigma }_{b}vgh$

mass of block $\left(m\right)=volume\times density=V\times S_b$

$\Rightarrow$ $m=S_{b}V$

Since, we know that gravitational potential energy of block at height $h$

$=mgh$

So, the gravitational potential energy of the block $=S_b{V}_{g}h$