Question

A body is moving in a straight line with a certain velocity. Another body with double the mass and half the velocity of the first, is moving in the straight line. What is the ratio of kinetic energy of second body with the fine body?

• A. 1:2
• B. 3:2
• C. 2:2
• D. 1:3

Answer 1

The correct option is A 1:2

Let the mass and velocity of 1st body be $mandv$ respectively.

Hence,

$K{E}_1=\frac{1}{2}m{v}^2$

and

$K{E}_2=\frac{1}{2}\times 2m\times (v/2{)}^2$

$K{E}_2=\frac{1}{4}m{v}^2$

Now,

$\frac{K{E}_2}{K{E}_1}=\frac{\frac{1}{4}m{v}^2}{\frac{1}{2}m{v}^2}$

$=\frac{1}{2}$