In each situation of Column I, uniform disc of mass and radius rolls on a rough fixed horizontal surface as shown. At (initially) the angular velocity of the disc is and velocity of the centre of mass of the disc is (in horizontal direction). The relation between and for each situation and also initial sense of rotation is given for each situation in column I. Then match the statements in Column I with the corresponding results in Column II 
ColumnI 
Column II 

(A) 
(p) 
The angular momentum of the disc about point A (as shown in the figure) remain conserved 

(B) 
(q) 
The kinetic energy of the disc after it starts rolling without slipping is less than its initial kinetic energy 

(C) 
(r) 
In the duration disc rolls with slipping, the friction acts on the disc towards the left 

(D) 
(s) 
In the duration disc rolls with slipping, the friction acts on the disc for some time to the right and for some time to the left 

CODES : 


A 
B 
C 
D 



a) 
C 
d 
b 
a 



b) 
a,c 
d,c 
c,d 
c,d 



c) 
b,a 
b,c 
d 
a,c 



d) 
a,b,c 
a,b,c 
a,b 
a,b,c 


In each situation of Column I, uniform disc of mass and radius rolls on a rough fixed horizontal surface as shown. At (initially) the angular velocity of the disc is and velocity of the centre of mass of the disc is (in horizontal direction). The relation between and for each situation and also initial sense of rotation is given for each situation in column I. Then match the statements in Column I with the corresponding results in Column II 
ColumnI 
Column II 

(A) 
(p) 
The angular momentum of the disc about point A (as shown in the figure) remain conserved 

(B) 
(q) 
The kinetic energy of the disc after it starts rolling without slipping is less than its initial kinetic energy 

(C) 
(r) 
In the duration disc rolls with slipping, the friction acts on the disc towards the left 

(D) 
(s) 
In the duration disc rolls with slipping, the friction acts on the disc for some time to the right and for some time to the left 

CODES : 


A 
B 
C 
D 



a) 
C 
d 
b 
a 



b) 
a,c 
d,c 
c,d 
c,d 



c) 
b,a 
b,c 
d 
a,c 



d) 
a,b,c 
a,b,c 
a,b 
a,b,c 


(d) Since all forces on the disc pass through the point of contact with the horizontal surface, the angular momentum of the disc about the point on the ground in contact with disc is conserved.Also the angular momentum of the disc in all cases is conserved about any point on the line passing through the point of contact and parallel to the velocity of the centre of mass The KE of the disc is decreased in all cases due to work done by friction. From the calculation of velocity of the lowest point on disc, the direction of friction in case (i), (ii) and (iv) is towards the left and in case it is towards the right The direction of frictional force cannot change in any given case 