The momentum of a body is increased by $50 \%$. The percentage increase in the kinetic energy of the body is ___________ $\%$.
Answer (integer)
125
Solution
<p>The momentum (p) and kinetic energy (K) of a body are related by the equations:</p>
<p>$p = mv$,</p>
<p>$K = \frac{1}{2}mv^2$,</p>
<p>where m is the mass and v is the velocity of the body.</p>
<p>We can express v in terms of p and m:</p>
<p>$v = \frac{p}{m}$,</p>
<p>and substitute this into the equation for K to get:</p>
<p>$K = \frac{p^2}{2m}$.</p>
<p>So, the kinetic energy is proportional to the square of the momentum.</p>
<p>If the momentum is increased by 50%, the new momentum is 1.5p, and the new kinetic energy is:</p>
<p>$K' = \frac{(1.5p)^2}{2m} = \frac{2.25p^2}{2m} = 2.25K$.</p>
<p>The percentage increase in the kinetic energy is then:</p>
<p>$\frac{K'-K}{K} \times 100 = \frac{2.25K - K}{K} \times 100 = 1.25 \times 100 = 125\%$.</p>
<p>So, the percentage increase in the kinetic energy of the body is 125%.</p>
About this question
Subject: Physics · Chapter: Rotational Motion · Topic: Centre of Mass
This question is part of PrepWiser's free JEE Main question bank. 158 more solved questions on Rotational Motion are available — start with the harder ones if your accuracy is >70%.