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9th Class Science Work and energy Question Bank Work, Energy and Power

  • question_answer
    In a rocket, fuel burns at the rate of\[1\,Kg\,{{s}^{-1}}\]. This fuel is ejected from the rocket with a velocity of\[60\,Km{{s}^{-1}}\]. This exerts a force, in newton, on the rocket of

    A)  \[60\,N\]             

    B)         \[600\,N\]

    C)  \[6,000\,N\]     

    D)         \[60,000\,N\]  

    Correct Answer: D

    Solution :

     Force\[=ma=m\times \frac{v}{t}=\frac{m}{t}\times v\] Now, \[\frac{m}{t}\,\,i.e.,\] the rate of loss of mass is given to be, \[1\,\,kg{{s}^{-1}}\] and the velocity is given to be\[60,000\,\,m{{s}^{-1}}\]. \[\therefore \]  Force\[=1\times 60,000\]                         \[=60,000\,\,N\]


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