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NEET Sample Paper NEET Sample Test Paper-38

  • question_answer
    An explosion blows a rock into three parts. Two parts go off at right angles to each other. These two are 1 kg first part moving with a velocity of \[12\,m{{s}^{-1}}\] and 2 kg second part moving with a velocity of \[8\,m{{s}^{-1}}.\]If the third part flies off with a velocity of \[4\,m{{s}^{-1}},\] its mass would be

    A)  5 kg         

    B)  7 kg

    C)  17 kg        

    D)  3 kg

    Correct Answer: A

    Solution :

     Apply law of conservation of linear momentum, Momentum of first par\[~=1\times 12=12\text{ }kg\,m{{s}^{-1}}\]t Momentum of the second part\[=2\times 8=16\text{ }kg\,m{{s}^{-1}}\] \[\therefore \] Resultant momentum \[=\sqrt{{{(12)}^{2}}+{{(16)}^{2}}}=20\,kg\,m{{s}^{-1}}\] The third part should also have the same momentum. Let the mass of the third part be M, then \[4\times M=20\] \[M=5\,kg\]


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