System of Particles and Rotational Motion - Result Question 50

54. A solid homogeneous sphere of mass $M$ and radius $R$ is moving on a rough horizontal surface, partly rolling and partly sliding. During this kind of motion of the sphere

[1988]

(a) total kinetic energy is conserved

(b) the angular momentum of the sphere about the point of contact with the plane is conserved

(c) only the rotational kinetic energy about the centre of mass is conserved

(d) angular momentum about the centre of mass is conserved.

Topic 4: Moment of Inertia, Rotational K.E. and Power

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Answer:

Correct Answer: 54. (b)

Solution:

  1. (b) Angular momentum about the point of contact with the surface includes the angular momentum about the centre. Due to friction linear momentum is conserved.