JEE Main 2014 · 6 Apr · Shift 1 · Physics Q3

← JEE Main 2014 · 6 Apr · Shift 1

PhysicsSingle correct+4 / -1Question 3 of 90

A mass 'm' is supported by a massless string wound around a uniform hollow cylinder of mass m and radius R. If the string does not slip on the cylinder, with what acceleration will the mass fall on release ?

A hollow cylinder of mass m and radius R on a fixed horizontal axle; a string wound on it hangs vertically from its right edge and carries a block of mass m.

\dfrac{2g}{3}

\dfrac g2

\dfrac{5g}{6}

g

Answer and worked solution

Official answer: B

For a hollow cylinder $I=mR^2$ . Then:

block: $mg-T=ma$ ;
cylinder: $TR=I\frac aR=mRa$ , so $T=ma$ .

Hence $mg=2ma$ and $a=\dfrac g2$ .

Topics:Torque and rotational dynamics Moment of inertia

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JEE Main 2014 · 6 Apr · Shift 1, Physics question 3