# JEE mechanics doubt!! plz help

Q. If angular velocity of a disc depends on angle rotated $\theta$ as $\omega$ =$\theta^{2}$ +$2\theta$, then its angular acceleration $\alpha$ at $\theta$=1 rad is

(1) 8 rad/$sec^{2}$
(2) 10 rad/$sec^{2}$
(3) 12 rad/$sec^{2}$
(4) None of these

Note by Akhilesh Chobey
5 years, 5 months ago

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First differentiate omega with respect to t to get the expression of alpha then put the value of omega at theta 1 and theta

- 5 years, 1 month ago

i think angular acc is dw/dt to find that : first find dw/dtheta and then as we know w = dtheta/dt

so now take out inverse of w which is dt/dtheta and now divide dw/dtheta and dt/dtheta

- 4 years, 3 months ago

since a(alpha) = dw/dt = (dw/ds )(ds/dt)=w(dw/ds).Hence ans will be 3*4=12

- 4 years, 1 month ago