Question

The weight of a body in air is $100N$. How much will it weigh in water, if it displaces $400cc$ of water?

• A. $96N$
• B. $94N$
• C. $98N$
• D. $noneofthese$

Answer 1

The correct option is A $96N$

Given that,

Weight of body in air = $100N$

Buoyant force = Weight of liquid displaced

Volume of water displaced = $400c{c}^2$

Density of water = $1g/cm3$

In this case,

$\rho =\frac{m}{V}$

$m=\rho \times V$

$m=1\times 400$

$m=400g$

We know that,

The weight of water displaced is

$W=m\times g$

$W=\frac{2}{5}\times 9.8$

$W=3.92N$

Now, weight of the object in water

$W=100-3.92$

$W=96.08$

$W=96N$

Hence, the weight of object in water is $96N$