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9th Class Science Force and laws of motion Question Bank Force and Laws of Motion

  • question_answer
    A diwali rocket is ejecting 0.05 kg of gases per second at a velocity of 400 m/sec. The accelerating force on the rocket is

    A)  20 dynes        

    B)         20 Newtons  

    C)  20 kg wt             

    D)         10 Newtons

    Correct Answer: B

    Solution :

                \[F=ma=\frac{dm}{dt}\times v\]             \[=5\times {{10}^{-2}}\times 4\times {{10}^{2}}\]             \[=\mathbf{20}\,\,\mathbf{Newtons}\]


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