Most Important Selected Qs for JEE AdvancedPhysicsOscillations
A uniform plank of mass m, free to move in horizontal direction, is placed on the top of a solid cylinder of mass 2 m and radius R. The plank is attached with one end of a mass less spring of force constant k and the other end of spring is fixed with a wall as shown in fig. The plank is shiftily displaced towards spring and released. There is no slipping anv where then
Options
- ATotal energy of the system, when compression is spring is x and velocity of plank is v, is 7 8 mv ^2+ 1 2 kx ^
- BAngular frequency of oscillation is 4 k 7 ~m
- CTime period of oscillation is 7 ~m 4 k
- DAngular frequency oscillation is 2 k 7 m
Correct answer
B. Angular frequency of oscillation is 4 k 7 ~m
Step-by-step solution
At the instant when velocity of plank is v velocity of C.M. of cylinder is V 2 and angular velocity of cylinder is aligned & E = 1 2 mv ^2+ 1 2 kx ^2+ 1 2 2 ~m ( v 2 )^2+ 1 2 I ( ~V / 2 R )^2 & I = 2 mR ^2 R = mR ^2 & = 7 8 mv ^2+ 1 2 kx ^2 aligned For free oscillation d E d t =0 a=- ( 4 k 7 m ) x ^2= 4 k 7 ~m and t = 2 =2 7 ~m 4 k