Three identical balls, with masses of M,2M, and 3M, are fastened to a massless rod of length L as shown. The rotational inertia about the left end of the rod is:

Question

anonymous · Answer

attachment

souvik · Answer

I=3M*0+2M*(L/2)^2+M*L^2

anonymous · Answer

I had solved it like that , then i had got the answer ( 3ML^2)/2
but the correct  answer was (3ML^2)/4  !!

souvik · Answer

@Vincent-Lyon.Fr

vincent-lyon.fr · Answer

The correct answer is the one you and souvik have given.

Facto before ML² MUST be greater than 1.

souvik · Answer

for any moment of inertia ML^2 is greater than 1?

vincent-lyon.fr · Answer

No, I mean numerical factor before ML² is greater than one.
This is because mass M lies at distance L of axis and moments of inertia are always positive additive.

souvik · Answer

o..got it..thank u Sir..

anonymous · Answer

@Vincent-Lyon.Fr ,,  Thanx a lot Sir ..
@souvik ,,  Thank for you too

souvik · Answer

you are welcome..:)