RAJASTHAN PMT Rajasthan - PMT Solved Paper-2010

  • question_answer
    The energy required to accelerate a car from 10 m/s to 20 m/s is how many times the energy required to accelerate the car from rest to 10 m/s?

    A)  Equal                                   

    B)  4 times

    C)  2 times               

    D)         3 times

    Correct Answer: D

    Solution :

    Kinetic energy for first condition                 \[=\frac{1}{2}m(v_{2}^{2}-v_{1}^{2})=\frac{1}{2}m({{20}^{2}}-{{10}^{2}})\]                 \[=150\,\,mJ\] \[KE\]for second condition                 \[=\frac{1}{2}m({{10}^{2}}-{{0}^{2}})=50\,\,mJ\] \[\therefore \]  \[\frac{{{(KE)}_{I}}}{{{(KE)}_{II}}}=\frac{150\,\,m}{50\,\,m}=3\]


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