Question

Two uniform circular discs, each of mass 1 kg and radius 20 cm are kept in contact about the tangent passing through the point of contact. Find the moment of inertia of the system about the tangent passing through the point of contact.

Answer 1

I think CM of circular dics is
${mr}^{2?}$

Answer 2

Hii dear,

◆ Answer- M.I. = 0.1 kgm^2

◆ Explaination-
# Given-
m = 1 kg
r = 20 cm = 0.2 m

# Solution-
M.I. about diameter of disc -
I = 1/4 mr^2

By parallel axis thm, M.I about tangent,
I' = I + mr^2
I' = 1/4 mr^2 + mr^2
I' = 5/4 mr^2

M.I. about common tangent between 2 discs-
M.I. = 2 × I'
M.I. = 2 × 5/4 mr^2
M.I. = 5/2 × 1 × (0.2)^2
M.I. = 0.1 kgm^2

M.I. about common tangent between 2 discs is 0.1 kgm^2.

Hope that is helpful...