JEE Main 2017 — Rotational Motion Question with Solution
From: JEE Main 2017 (Online) 8th April Morning Slot
Question
A uniform disc of radius R and mass M is free to rotate only about its axis. A string is wrapped over its rim and a body of mass m is tied to the free end of the string as shown in the figure. The body is released from rest. Then the acceleration of the body is :
This question includes a diagram. The text above accompanies the figure.
Choose an option
Show full solutionCorrect option: A
Correct answer
A
Step-by-step explanation
From figure, we can say
ma = mg T . . . . . (1)
Moment of inertia of a uniform disc,
I = MR2
and the acceleration of the disc, a = R
We know,
Torque = I = RT
RT = M R2 =
T =
Putting the value of T in eq (1).
ma = mg
a ( m + ) = mg
a =
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