Easy MCQ +4 / -1 PYQ · JEE Mains 2023

Two bodies are having kinetic energies in the ratio 16 : 9. If they have same linear momentum, the ratio of their masses respectively is :

  1. A $3: 4$
  2. B $4: 3$
  3. C $9: 16$ Correct answer
  4. D $16: 9$

Solution

The kinetic energy of a body of mass $m$ and velocity $v$ is given by $K=\frac{1}{2}mv^2$. Since the bodies have the same linear momentum, we can write: <br/><br/> $p=mv$ <br/><br/> where $p$ is the linear momentum of the bodies. <br/><br/> Let the masses of the two bodies be $m_1$ and $m_2$ and their kinetic energies be $K_1$ and $K_2$, respectively. Then, we have: <br/><br/> $\frac{K_1}{K_2}=\frac{16}{9}$ <br/><br/> $\frac{1}{2}m_1v_1^2\div\frac{1}{2}m_2v_2^2=\frac{16}{9}$ <br/><br/> Since $p=mv$, we have $v_1=\frac{p}{m_1}$ and $v_2=\frac{p}{m_2}$. Substituting these in the above equation, we get: <br/><br/> $\frac{m_2}{m_1}=\frac{9}{16}$ <br/><br/> Therefore, the ratio of the masses of the two bodies is $\boxed{9:16}$.

About this question

Subject: Physics · Chapter: Work, Energy and Power · Topic: Work Done by a Force

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