1) A solid cylinder of mass m and radius R rolls down the inclined plane without slipping. The speed of its C.M. when it reaches the bottom is A) √2gh B) √4gh3 C) √34gh D) √4gh Answer: Option BExplanation:By energy conservation (K.E)i + (P.E)i = (K.E)f+ (P.E)f (K.E)i =0,(P.E)i = mgh, (P.E)f = 0 (K.E)f = 12Iω2+12mv2 For the solid cylinder, the moment of inertia, I = 12mR2 So, mgh = 12(12mR2)(v2R2)+12mv2 v = √4gh3