BCECE Engineering BCECE Engineering Solved Paper-2010

  • question_answer If the external forces acting on a system have zero resultant, the centre of mass

    A)  may move but not accelerate

    B)  may accelerate

    C)  must not move

    D)  None of die above

    Correct Answer: A

    Solution :

    According to the equation of motion of the centre of mass \[M{{\vec{a}}_{CM}}={{\vec{F}}_{ext}}\]                 If \[{{\vec{F}}_{ext}}=0,{{\vec{a}}_{CM}}=0\]                 \[\therefore \]  \[{{\vec{v}}_{CM}}=\text{constant}\] ie, if no external force acts on a system the velocity of its centre of mass remains constant. Thus, the centre of mass may move but not accelerate.


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