Laws of Motion

  • Question 489
    CBSEENPH11020382

    A block of mass 0.50 kg is moving with a speed of 2.00 m/s on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

    • 0.16 J

    • 1.00 J

    • 0.67 J

    • 0.34 J

    Solution

    C.

    0.67 J

    m1u1 + m2u2 = (m1 + m2)v
    v = 2/3 m/s
    Energy space loss space equals space 1 half space left parenthesis 0.5 right parenthesis space straight x space left parenthesis 2 right parenthesis squared space minus space 1 half space left parenthesis 1.5 right parenthesis space straight x space open parentheses 2 over 3 close parentheses squared
space equals space 0.67 space straight J

    Question 490
    CBSEENPH11020392

    A block of mass ‘m’ is connected to another block of mass ‘M’ by a spring (mass less) of spring constant ‘k’. The blocks are kept on a smooth horizontal plane. Initially the blocks are at rest and the spring is stretched. Then a constant force ‘F’ starts acting on the block of mass ‘M’ to pull it. Find the force on the block of mass ‘m’.

    • mF/M

    • (M+m)F/m

    • mF/(m+ M)

    • MF (m+M)

    Solution

    C.

    mF/(m+ M)

    Question 491
    CBSEENPH11020401

    A particle is projected at 60° to the horizontal with a kinetic energy K. The kinetic energy at the highest point is 

    • K

    • 0

    • K/2

    • K/4

    Solution

    D.

    K/4

    Question 492
    CBSEENPH11020406

    A bomb of mass 16 kg at rest explodes into two pieces of masses of 4 kg and 12 kg. The velocity of the 12 kg mass is 4 ms−1 . The kinetic energy of the other mass is

    • 144 J

    • 96 J

    • 288 J

    • 192 J

    Solution

    C.

    288 J

    m1v1 = m2v2
    KE space equals space 1 half straight m subscript 2 straight v subscript 2 superscript 2 space
space equals space 1 half space straight x space 4 space straight x space 144 space equals space 288 space straight J

    NCERT Book Store

    NCERT Sample Papers

    Entrance Exams Preparation