# Figure (a) shows two disc and , rotating about a common axis with constant angular speeds and ,respectively. Moment of inertia of disc is and that of disc is .The discs are then gently pushed towards each other by forces thatact along the axis. Finally, the discs rub against each other and attain a common angular speed , as shown in figure (b). Match Colums I and II Column-I Column- II (A) As the discs stick together, the final angular speed, (p) Will be zero (B) Torque on each disc, due to the force applied on the disc (q) Will be decreasing (C) When the discs are rubbing against each other, the kinetic energy of their system (r) (D) Angular momentum of the system (s) There will be loss of energy in doing work against the non-conservative internal forces CODES :   A B C D     a) B c a       b) c a b,d does notma     c) a c b       d) d a c

## Question ID - 101102 :- Figure (a) shows two disc and , rotating about a common axis with constant angular speeds and ,respectively. Moment of inertia of disc is and that of disc is .The discs are then gently pushed towards each other by forces thatact along the axis. Finally, the discs rub against each other and attain a common angular speed , as shown in figure (b). Match Colums I and II Column-I Column- II (A) As the discs stick together, the final angular speed, (p) Will be zero (B) Torque on each disc, due to the force applied on the disc (q) Will be decreasing (C) When the discs are rubbing against each other, the kinetic energy of their system (r) (D) Angular momentum of the system (s) There will be loss of energy in doing work against the non-conservative internal forces CODES :   A B C D     a) B c a       b) c a b,d does notma     c) a c b       d) d a c

3537

 (b) Force passes through the CM of the discs and hence its torque about CM has to be zero Also, force of friction will be internal After the discs stick together, let the final angular speed be   When the discs rub against each other, the kinetic energy will decrease as there will be some loss of energy in doing work against the non-conservative force of friction Loss of KE  