JEE Main & Advanced Physics Work, Energy, Power & Collision / कार्य, ऊर्जा और शक्ति Question Bank Self Evaluation Test - Work, Energy and Power

  • 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 pg. The instantaneous velocity of this car is proportiourl to:

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

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

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

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

    Correct Answer: B

    Solution :

    [b] Constant power of car \[{{P}_{0}}=F.V=ma.v\] \[{{P}_{0}}=m\frac{dv}{dt}.v\] \[{{P}_{0}}dt=mvdv\] Integrating \[{{P}_{0}}.t=\frac{m{{v}^{2}}}{2}v=\sqrt{\frac{2{{P}_{0}}t}{m}}\] \[\because ~~{{P}_{0}},\]m and 2 are constant  \[\therefore \text{ }v\text{ }\propto \sqrt{t}\]


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