NEET Physics Work, Energy, Power & Collision / कार्य, ऊर्जा और शक्ति NEET PYQ-Work Energy Power and Collision

  • question_answer
    A car of mass m starts from rest and accelerates so that the instantaneous power delivered to the car has a constant magnitude \[{{p}_{0}}\]. The instantaneous velocity of this car is proportional to                         [AIPMT (M) 2012]

    A) \[{{t}^{2}}{{p}_{0}}\]

    B) \[{{t}^{1/2}}\]

    C) \[{{t}^{-1/2}}\]

    D) \[t/\sqrt{m}\]

    Correct Answer: B

    Solution :

    Power    \[{{P}_{0}}=Fv\]
                            \[=\left( m\frac{dv}{dt} \right)v\]
                            \[=mv\frac{dv}{dt}\]
    Integrating both sides
    \[\int_{{}}^{{}}{{{p}_{0}}dt=\int_{{}}^{{}}{mv\,dv}}\]
    \[{{p}_{0}}t=\frac{m{{v}^{2}}}{2}\]
    \[{{v}^{2}}=\frac{2{{p}_{0}}t}{m}\]
                            \[v\propto {{t}^{1/2}}\]


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