Laws of Motion

  • Question 509
    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 510
    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
    Question 511
    CBSEENPH11020440

    A mass ‘m’ moves with a velocity v and collides inelastically with another identical mass. After collision, the 1st mass moves with velocity v/√3 in a direction perpendicular to the initial direction of motion. Find the speed of the 2nd mass after collision

    • v

    • √3 v

    • 2v/√3

    • v/√3

    Solution

    C.

    2v/√3

    mv= mv1 cos = θ

    0 space equals space fraction numerator mv over denominator square root of 3 end fraction space minus mv subscript 1 sinθ
therefore space straight v subscript 1 space equals space fraction numerator 2 over denominator square root of 3 end fraction straight v

    Question 512
    CBSEENPH11020445

    Consider a car moving on a straight road with a speed of 100 m/s. The distance at which car can be stopped is [µ =k 0.5]

    • 800 m

    • 1000 m

    • 600 m

    • 900 m

    Solution

    B.

    1000 m

    straight mu subscript straight k mgs space equals space 1 half mu squared
straight s equals space fraction numerator straight u squared over denominator 2 straight mu subscript straight k straight g end fraction space equals space 1000 space straight m

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