NEET Physics NLM, Friction, Circular Motion NEET PYQ-NLM Friction Circular Motion

  • question_answer
    A stationary particle explodes into two particles of masses \[{{m}_{1}}\] and \[{{m}_{2}}\] which move in opposite directions with velocities \[{{v}_{1}}\] and \[{{v}_{2}}\]. The ratio of their kinetic energies \[{{E}_{1}}/{{E}_{2}}\] is:   [AIPMT 2003]

    A) 1

    B) \[{{m}_{1}}{{v}_{2}}/{{m}_{2}}{{v}_{1}}\]

    C) \[{{m}_{2}}/{{m}_{1}}\]

    D) \[{{m}_{1}}/{{m}_{2}}\]

    Correct Answer: C

    Solution :

    Key Idea : For a exploding body, linear momentum is conserved.
                From conservation of linear momentum,
                            \[{{P}_{inititial}}={{P}_{final}}\]
                            \[0={{m}_{1}}{{v}_{1}}-{{m}_{2}}{{v}_{2}}\]
                or         \[{{m}_{1}}{{v}_{1}}={{m}_{2}}{{v}_{2}}\]
                or         \[\frac{{{v}_{1}}}{{{v}_{2}}}=\frac{{{m}_{2}}}{{{m}_{1}}}\]                                  …(i)
                Thus, ratio of kinetic energies,
                            \[\frac{{{E}_{1}}}{{{E}_{2}}}=\frac{\frac{1}{2}{{m}_{1}}v_{1}^{2}}{\frac{1}{2}{{m}_{2}}v_{2}^{2}}=\frac{{{m}_{1}}}{{{m}_{2}}}\times {{\left( \frac{{{m}_{2}}}{{{m}_{1}}} \right)}^{2}}\]\[=\frac{{{m}_{2}}}{{{m}_{1}}}\]


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