Question

A body of mass 1 kg has a kinetic energy of motion 8 J. Its linear momentum is equal to:

• A. $2kgm{s}^{-1}$
• B. $4kgm{s}^{-1}$
• C. $6kgm{s}^{-1}$
• D. $8kgm{s}^{-1}$

Answer 1

The correct option is B $4kgm{s}^{-1}$

We know that,

$K{l}^2=\frac{m{V}^2}{2}$ and $P$ ( linear momentum ) $=mv$

So, $KE=\frac{(mV{)}^2}{2m}=\frac{P^2}{2m}$

$\Rightarrow P^2=2mKE\Rightarrow P=\sqrt{\left(2m\right)\left(KE\right)}$

Here, $m=1$ and $KE=85$. So,

$P=\sqrt{2\times \left(1\right)\left(8\right)}=\sqrt{16}=4mkg{s}^{-1}$

Option $-B$ is correct.