JEE Main & Advanced Physics Vectors Question Bank Addition and Subtraction of Vectors

  • question_answer
    An object of m kg with speed of v m/s strikes a wall at an angle q and rebounds at the same speed and same angle. The magnitude of the change in momentum of the object will be

    A)                 \[2m\,v\,\cos \theta \]

    B)                             \[2\,m\,v\,\sin \theta \]

    C)                 0

    D)                 \[2\,m\,v\]

    Correct Answer: A

    Solution :

                        \[{{\overrightarrow{P}}_{1}}=m\,v\,\sin \theta \,\hat{i}-m\,v\,\cos \theta \,\hat{j}\]                 and \[{{\overrightarrow{P}}_{2}}=m\,v\,\sin \theta \,\hat{i}+\,m\,v\,\cos \theta \,\hat{j}\]                 So change in momentum                 \[\overrightarrow{\Delta P}={{\overrightarrow{P}}_{2}}-{{\overrightarrow{P}}_{1}}=2\,m\,v\,\cos \theta \,\hat{j},\]\[|\Delta \overrightarrow{P}|\,=2\,m\,v\,\cos \theta \]


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