Saved Bookmarks
| 1. |
A plank P is placed on a solid cylinder S, which rolls on a horizontal surface. The two are of equal mass. There is no slipping at any of the surfaces in contact. The ratio of the kinetic energy of P to that of S is (a) 1 : 1 (b) 2 : 1 (c) 8 : 3 (d) 11 : 8 |
|
Answer» Correct Answer is: (c) 8 : 3 Let v be the velocity of the centre of mass of the cylinder S. Then, the velocity of P is 2v. ∴ KE of P is 1/2 (m)(2v)2 = 2mv2. KE of S is 1/2 mv2(1 + k2/r2) = 1/2 mv2(1 + 1/2) = 3/4 mv2. ∴ The ratio becomes 2mv2 : 3/4 mv2 = 8 : 3. |
|