9th Class Science Work and energy Question Bank Work Power and Energy Summative Objective Problems

  • question_answer
    A 1000 kg car can accelerate from rest to a speed of 25 m/s in 10 s. What average power must the engine of the car produce in order to cause this acceleration. Neglect the friction loss.

    A)  11.25 kW                            

    B)  21.25 kW

    C)  31.25 kW            

    D)  41.25 kW

    Correct Answer: C

    Solution :

      We know, \[P=\frac{W}{t}\] her, the work done in accelerating the car (W) = Increase in KE \[\therefore P=\frac{\frac{1}{2}m{{v}^{2}}-\frac{1}{2}m{{u}^{2}}}{t}=31.25\,kW\]           


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