A triangular plate of uniform thickness and density is made to rotate about an axis perpendicular to the plane of the paper and
(i) passing through `A`,
(ii) passing through `B`, by the application of some force `F` at `C` (mid - point AB) as shown in the figure. In which case angular acceleration is more ?
.

Options

A. in case a
B. in case b
C. both a and b
D. none of these

Answer

B

Explanation

`tau-Ialpha` or `a=tau/I`
Here as the force is applied at midpoint
`tau_(A)=tau_(B)=FxxL/2`
And as moment of inertia depends on the distributioin of mass w.r.t the axis of rotation hence
`I_(A)gtI_(B)` or `alpha_(A)gtalpha_(B)`
i.e angular acceleration is more in case `b`.