Answer:
G =67.74
Step-by-step explanation:
Given that
length l=2.4 m
Outside diameter= 16 cm
Inside diameter= 15 cm
Speed N =900 RPM
We know that

Where r is the radius V is the velocity.
So mean radius 
 

r = 7.5 cm 
We know that 



V=ω x r
V= 94.24 x 0.075 m/s 
V= 7.06 m/s


G =67.74