Question

mass of one body is thrice the mass of other body. the speed of first body is half the speed of second body. find the ratio of their kinetic energy​

Answer 1

Answer: Mass of one body is thrice the mass of other body. the speed of first body is half the speed of second body. The ratio of their kinetic energy​ is 3:4

Explanation:

Let A  be the first body and B  be the second body, the equation for Kinetic Energy of a body

$E=\frac{1}{2} mv^{2}$

where $m$ is the mass of the body and $v$ is the velocity or speed of the body.

As the mass of the first body is three times the mass of other body and speed is half of the second body,

Kinetic energy of the first body can be substituted as,

$E(A)=\frac{1}{2} 3m\frac{v}{2} ^{2}$ and

Kinetic energy of the second body can be substituted as,

$E(B)=\frac{1}{2} mv^{2}$,

Therefore

$\frac{E(A)}{E(B)} =\frac{\frac{1}{2}3m\frac{v}{2} ^{2} }{\frac{1}{2}mv^{2} } =\frac{3}{4}$

Therefore the ratio of their kinetic energy is 3:4