Physics · Rotational Dynamics

JEE Advanced 2022 — Paper 1 — Question 23

At time t=0\mathrm{t}=0, a disk of radius 1 m starts to roll without slipping on a horizontal plane with an angular acceleration of α=23rads−2\alpha=\frac{2}{3} \mathrm{rad} \mathrm{s}{ }^{-2}. A small stone is stuck to the disk. At t=0\mathrm{t}=0, it is at the contact point of the disk and the plane. Later, at time t=st=\sqrt{ } \mathrm{s}, the stone detaches itself and flies off tangentially from the disk. The maximum height (in m ) reached by the stone measured from the plane is 12+x10\frac{1}{2}+\frac{x}{10}. The value of xx is \qquad [Take g=10 ms−2\mathrm{g}=10 \mathrm{~ms}^{-2}.]

Answer: 0.52

Numerical answer — enter this value.

Step-by-step solution

θ=12αt2\theta=\frac{1}{2} \alpha \mathrm{t}^{2} =12×23π=π3=60∘=\frac{1}{2} \times \frac{2}{3} \pi=\frac{\pi}{3}=60^{\circ}

vcm=αt\mathrm{v}_{\mathrm{cm}}=\alpha \mathrm{t}

Net velocity of point P is V=αt\mathrm{V}=\alpha t

at an angle 60∘60^{\circ}

with horizontal uy=αtsin⁡60∘u_{y}=\alpha t \sin 60^{\circ}

ymax⁡=12+uy22 g=12+α2t22034=12+π60\mathrm{y}_{\max }=\frac{1}{2}+\frac{\mathrm{u}_{\mathrm{y}}^{2}}{2 \mathrm{~g}}=\frac{1}{2}+\frac{\alpha^{2} \mathrm{t}^{2}}{20} \frac{3}{4}=\frac{1}{2}+\frac{\pi}{60}

x=0.52\mathrm{x}=0.52

Solution figure

Answer key and solution verified before publishing.

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Exam
JEE Advanced 2022
Paper
Paper 1
Subject
Physics
Chapter
Rotational Dynamics
Topic
Rolling Motion