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

  • question_answer
    A body of mass 2 kg is initially moving with a velocity of 4 m/sec. Now a force of 1.25 Newtons acts for 8 sec. Then a force of 2.5 N acts for 8 sec. The final velocity of the body is

    A)  12.55 m/sec

    B)  17 m/sec

    C)  19 m/sec  

    D)  25 m/sec

    Correct Answer: C

    Solution :

     Acceleration produced by\[1.25\,\,N\]             \[=\frac{F}{m}=\frac{1.25}{2}=0.625\] Acceleration produce by\[2.5\,\,N=\frac{2.5}{2}=1.25\] \[\therefore \]      \[v=u+at\]                \[=4+0.625\times 8+1.25\times 8\]


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