Question

If the kinetic energy and momentum of a body is 100 J and 20 kg.m/s, the mass of the body is

• A. 1.5 kg
• B. 2 kg
• C. 3 kg
• D. 4 kg

Answer 1

The correct option is B 2 kg

Kinetic energy=$1/2m{v}^2$

And momentum$=mv$

As both the unit is in SI.

So, $\frac{K.E}{momentum}=\frac{\frac{1}{2}m{v}^2}{mv}=\frac{1}{2}v$

$\frac{1}{2}v=\frac{100}{20}=5$

$v=10m/s$

As given, momentum=mv=20 kg.m/s

$m\ast 10=20$

$m=2kg$