Rotational MotionEasy
Question
A disc of mass M and radius R is rolling with angular speedc ω on a horizontal plane asshown. The magnitude of angular momentum of the disc about the origion O is
Options
A.
MR2 ω
MR2 ωB.MR2 ω
C.
MR2 ω
MR2 ωD.2MR2 ω
Solution
From the theorem
.........(i)
We may write
Angular momentum about O = Angular momentum about
CM + Angular momentum of CM about origin
∴ L0 = Iω + MRv
=
MR2 ω = MR(Rω) = 
MR2ω
Note that in this case both the terms in Eq (i) i.e.,
have the same direction ⎔ L0 = Iω + MRv. We will use L0 = Iω ~ MRv if they are in opposite direction as shown in the figure (b).
.........(i)We may write
Angular momentum about O = Angular momentum about
CM + Angular momentum of CM about origin
∴ L0 = Iω + MRv
=
MR2 ω = MR(Rω) = MR2ωNote that in this case both the terms in Eq (i) i.e.,
have the same direction ⎔ L0 = Iω + MRv. We will use L0 = Iω ~ MRv if they are in opposite direction as shown in the figure (b).Create a free account to view solution
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