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
The answer is (3) but i am not getting a solution so someone please help by providing one. Thanks!

#Mechanics #JEE #JEEPhysics

Easy Math Editor

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Comments

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

Vipra Goyal - 6 years, 8 months 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

vaibhav Chaturvedi - 5 years, 10 months ago

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

PIYUSH BHARTI - 5 years, 8 months ago

Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$