3 Marks Question

Question

Asolid disc and a ring, both of radius 10cm are placed on a horizontal table simultaneously, with initial angular speed equal to 10 rad s-1?. Which of the two will start to roll earlier? The coefficient of kinetic friction is

Vidyadip · Accepted Answer

As motion starts due to friction, F = ma _ k mg=ma = _ k g Torque due to friction =I _ k mgR=I = _ k mgR I Rolling begins, when v= But v=0+ = _ k gt and = _0+ = _0- _ k mgR I t v R = _0 _ k mgR I t = R _0 _ k g ( I+mR^2 I ) For disc, I=mR^2 =0.53s For ring, I=mR^2 =0.80s Thus, disc begins to roll earlier.

Systems of Particles and Rotational Motion — Physics STD 11 Science — Question