A particle of mass $m$ has momentum $p$. Its kinetic energy is given by:
A$\dfrac{p}{2m}$
B$\dfrac{p^2}{2m}$
C$2mp^2$
D$\dfrac{m^2}{2p}$
Answer & Solution
Correct answer: B. $\dfrac{p^2}{2m}$
Using $p=mv$ and $K=\frac12 mv^2$, we substitute $v=p/m$ to get $K=\frac12 m\left(\frac{p}{m}\right)^2=\frac{p^2}{2m}$. This relation is often used in JEE Main problems involving momentum and energy together.
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