NEET Sample Paper NEET Sample Test Paper-81

  • question_answer
    A metre scale is standing vertically on the earth's surface on one of its ends. It now falls on the earth without slipping. Find the velocity with which the free end of the scale strikes the earth \[(g =\,\,9.8 m/{{s}^{2}})\]

    A) 10.8 m/s                      

    B) 5.4 m/s

    C) 2.7 m/s                        

    D) None of these

    Correct Answer: B

    Solution :

    Here, the loss in potential energy is equal to the gain in the rotational kinetic energy. Hence \[\therefore \,\,\,\,\operatorname{mhg}\,\,=\, \frac{1}{2}\,l{{\omega }^{2}}\] \[\operatorname{m} \left( 9.8 \right) \left( 0.5 \right) = \frac{1}{2}\,\,\left( \frac{m}{3} \right)\,{{\omega }^{2}}~~~~~[as r= 1 m]\] Or         \[\omega =\sqrt{(3\times 9.8)}\,\,=\,\,\sqrt{(29.4)}\,\,=\,\,5.4\] Further, \[\operatorname{v} =r\omega =1 \times  5.4 = 5.4 = 5.4 m/s\]


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