Laws of Motion

  • Question 501
    CBSEENPH11020431

    Out of the following pair, which one does NOT have identical dimensions is

    • angular momentum and Planck’s constant

    • impulse and momentum

    • moment of inertia and moment of a force

    • work and torque

    Solution

    C.

    moment of inertia and moment of a force

    Question 502
    CBSEENPH11020437

    A body A of mass M while falling vertically downwards under gravity breaks into two parts; a body B of mass 1/3 M and a body C of mass 2/3 M. The centre of mass of bodies B and C taken together shifts compared to that of body A towards

    • depends on height of breaking

    • does not shift

    • body C

    • body B

    Solution

    B.

    does not shift

    No horizontal external force is acting
    ∴ = acm =0
    since vcm= 0
    ∴∆xcm = 0

    Question 503
    CBSEENPH11020438

    A particle of mass 0.3 kg is subjected to a force F=−kx with k=15 N/m. What will be its initial acceleration if it is released from a point 20 cm away from the origin?

    • 3 m/s2

    • 15 m/s2

    • 5 m/s2

    • 10 m/s2

    Solution

    D.

    10 m/s2

    a = kx/m =10m /s2

    Question 504
    CBSEENPH11020439

    The block of mass M moving on the frictionless horizontal surface collides with a spring of spring constant K and compresses it by length L. The maximum momentum of the block after collision is

    • square root of MK L
    • KL2/2M

    • zero

    • ML2/K

    Solution

    A.

    square root of MK L 1 half KL squared space equals space fraction numerator straight P squared over denominator 2 straight m end fraction
therefore space straight P space equals space square root of MK straight L

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