Q.

A solid sphere (A) of mass 5m and spherical shell (B) of mass m, both having same radius, are placed on a rough surface. When a force of same magnitude is applied tangentially at the highest points of A and B, they start rolling without slipping with an acceleration of aA and aB, respectively. The ratio of aA and aB is ________.      [2026]

1 5 : 21  
2 6 : 10  
3 21 : 25  
4 1 : 5  

Ans.

(1)

τp=Ipα⇒F(2R)=IaR

a=2FR2I⇒aAaB=IBIA

Solid sphere (A):  IA=25(5m)R2+(5m)R2=7mR2

Spherical shell (B):  IB=23mR2+mR2=53mR2

aAaB=IBIA=53mR27mR2=521