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JEE Advanced 2021Paper 2
Exam
JEE Advanced
Year
2021
Paper
Paper 2
Subject
Physics
Chapter
Rotational Motion

JEE Advanced 2021 · Paper 2 · Physics · Rotational Motion

A pendulum consists of a bob of mass m=0.1 ~kg and a massless...

A pendulum consists of a bob of mass m=0.1 kgm=0.1 \mathrm{~kg} and a massless inextensible string of length L=1.0 mL=1.0 \mathrm{~m}. It is suspended from a fixed point at height H=0.9 mH=0.9 \mathrm{~m} above a frictionless horizontal floor. Initially, the bob of the pendulum is lying on the floor at rest vertically below the point of suspension. A horizontal impulse P=0.2 kg−m/sP=0.2 \mathrm{~kg}-\mathrm{m} / \mathrm{s} is imparted to the bob at some instant. After the bob slides for some distance, the string becomes taut and the bob lifts off the floor. The magnitude of the angular momentum of the pendulum about the point of suspension just before the bob lifts off is J kg−m2/sJ \mathrm{~kg}-\mathrm{m}^{2} / \mathrm{s}. The kinetic energy of the pendulum just after the liftoff is KK Joules.
The value of JJ is ____.A pendulum consists of a bob of mass m=0.1 ~kg and a massless inextensible string of length L=1.0 ~m . It is suspended

Correct answer

0

Step-by-step solution

A pendulum consists of a bob of mass m=0.1 ~kg and a massless inextensible string of length L=1.0 ~m . It is suspended

The magnitude of the angular momentum of the pendulum about the point of suspension just before the bob lifts off is,

Angular momentum about top point L=mV×0.9L = mV \times 0 . 9

L=0.2×0.9L = 0 . 2 \times 0 . 9

⇒L=0.18kgm−2s⇒ L = 0 . 18kg{m}^{- 2}s

Hence, J=0.18J = 0 . 18.

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