Medium INTEGER +4 / -1 PYQ · JEE Mains 2023

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>$K&#39; = \frac{(1.5p)^2}{2m} = \frac{2.25p^2}{2m} = 2.25K$.</p> <p>The percentage increase in the kinetic energy is then:</p> <p>$\frac{K&#39;-K}{K} \times 100 = \frac{2.25K - K}{K} \times 100 = 1.25 \times 100 = 125\%$.</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

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