Single correct option
A uniform solid sphere of mass and radius is projected with speed along a rough horizontal floor with no initial spin. The coefficient of friction between sphere and floor is . After it starts rolling without slipping, it moves onto a long, rough incline (the transition is smooth and no energy is lost at the junction; rolling without slipping continues on the incline) and rolls up. The maximum vertical height reached by its centre above its height on the floor is
- A.
- B.
- C.
- D.
Show answer and solution
Answer: (D)
On the floor, friction acts at the contact point, so angular momentum about any point on the floor line is conserved: with at the end of slipping. This gives , so (independent of ); the rest of the kinetic energy, of the initial value, is lost as heat during slipping. On the incline rolling is without slipping, so mechanical energy is conserved: . Hence . Option (A) assumes no loss of energy during slipping and ignores rotation, (B) ignores the rotational energy on the incline, and (C) assumes no energy loss at all during slipping. The correct option is (D).
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