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MDCAT Physics QUESTION #4391
Question 1
If $P$ is the momentum of an object and $m$ is its mass, then its kinetic energy is:
  • $\dfrac{P}{2m}$
  • $\dfrac{P^2}{2m}$✔️
  • $\dfrac{1}{2}Pm^2$
  • $\dfrac{1}{2}P^2m$
Correct Answer Explanation
$KE = \dfrac{1}{2}mv^2$. Since $P = mv$, we have $v = \dfrac{P}{m}$. Substituting: $KE = \dfrac{1}{2}m\left(\dfrac{P}{m}\right)^2 = \dfrac{1}{2}m \cdot \dfrac{P^2}{m^2} = \dfrac{P^2}{2m}$.