2. Questions Bank
  3. 9th Class
  4. Science
  5. Work and energy

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

  • question_answer
    An elevator is designed to lift a load of 1000 kg through 6 floors of a building averaging 3.5 m per floor in 6 s. The power of the engine of the elevator neglecting the other losses is given by

    A)  20 kW                                  

    B)  13.6 kW

    C)  40.5 kW                              

    D)  34.3 kW

    Correct Answer: D

    Solution :

      Given, \[m=1000\,\,kgt=6s\] Height of single floor (h) = 3.5 m For six floors height \[(h)=6\times 3.5=21\,m\] \[p=?\] We know, \[P=\frac{mgh}{t}\] \[\Rightarrow \frac{1000\times 9.8\times 21}{6}=34300\,W\] or \[34.3\text{ }kW\]


You need to login to perform this action.
You will be redirected in 3 sec spinner