Q.

The pulley shown in figure is made using a thin rim and two rods of length equal to diameter of the rim. The rim and each rod have a mass of M. Two blocks of mass M and m are attached to two ends of a light string passing over the pulley, which is hinged to rotate freely in vertical plane about its center. The magnitude of the acceleration experienced by the blocks is ______ (assume no slipping of string on pulley).   [2026]

1 (M-m)g[(83) M+m]  
2 (M-m)g2M+m  
3 (M-m)gM+m  
4 (M-m)g[(136)M+m]  

Ans.

(1)

Mg-T2=Ma    ...(1)

T1-mg=ma    ...(2)

(T2-T1)r=Iar    ...(3)

(1)+(2)+(3)

(M-m)g=(M+m+Ir2)a

Here I=Mr2+M×(2r)212×2

=(1+23)Mr2

=53Mr2

(M-m)g=[M+m+5M3]a

a=(M-m)g[M+m+5M3]