Manipal Medical Manipal Medical Solved Paper-2007

  • question_answer
    A ball of mass 2 kg and another of mass 4 kg are dropped together from a 60 ft tall building. After a fall of 30 ft each towards earth, their respective kinetic energies will be in the ratio of

    A)  \[\sqrt{2}:1\]        

    B)  \[1:4\]

    C)  \[1:2\]         

    D)  \[1:\sqrt{2}\]

    Correct Answer: C

    Solution :

     Key Idea: In a free fall, two balls of different mass will acquire the same velocity after falling through same height. From key idea,\[{{v}_{1}}={{v}_{2}}=v\]at a 30 ft from falling point. Here, \[{{m}_{1}}=2kg,{{m}_{2}}=4kg\] Thus,    \[\frac{{{K}_{1}}}{{{K}_{2}}}=\frac{\frac{1}{2}{{m}_{1}}{{v}^{2}}}{\frac{1}{2}{{m}_{2}}{{v}^{2}}}=\frac{{{m}_{1}}}{{{m}_{2}}}=\frac{2}{4}=\frac{1}{2}\]


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