Home
Class 11
PHYSICS
A jester in a circus is standing with hi...

A jester in a circus is standing with his arms extended on a turntable rotating with angular velocity c. He brings his arms closer to his body so that his moment of inertia is reduced to one third of the original value. Find his new angular velocity [Given: There is no external torque on the turn table in the given situation.]

Text Solution

Verified by Experts

Let the moment of inertia of the jester with his arms extended bel. As there is no external torque acting on the jester and the tum table, his total angular momentum is conserved. We can write the equation,
`I_(i) omega_(i)=I_(f) omega_(f)`
`I_(i) omega_(i)=(1)/(3) I_(i) omega_(f)[ :. I_(f)=(1)/(3)I_(i)]`
`omega_(f)=3omega_(i)`
The above result tells that the final angular velocity is three times that of initial angol velocity
Promotional Banner

Topper's Solved these Questions

  • MOTION OF SYSTEM OF PARTICLES AND RIGID BODIES

    FULL MARKS|Exercise TEXTUAL QUESTIONS SOLVED ( MULTIPLE CHOICE QUESTIONS:)|15 Videos

  • MOTION OF SYSTEM OF PARTICLES AND RIGID BODIES

    FULL MARKS|Exercise TEXTUAL QUESTIONS SOLVED ( SHORT ANSWER QUESTIOS)|17 Videos

  • LAW OF MOTION

    FULL MARKS|Exercise ADDITIONAL QUESTIONS SOLVED (SHORT ANSWER QUESTIONS (3 MARKS & NUMERICALS))|16 Videos

  • NATURE OF PHYSICAL WORLD AND MEASUREMENT

    FULL MARKS|Exercise ADDITIONAL QUESTIONS SOLVED ( SHORT ANSWER QUESTIONS (2 MARK))|20 Videos

Similar Questions

Explore conceptually related problems

A man is sitting on a rotating stool with his arms outstretched. If suddenly he folds his arms the angular velocity of the man would

A child stands at the centre of turn table with his two arms out stretched. The turn table is set rotating with an angular speed of 40 rpm. How much is the angular speed of the child if he folds his hands back and thereby reduces his moment of inertia to 2/5 times the initial value? Assume that the turn table rotates without friction (ii) Show that the child's new kinetic energy of rotation is more than the initial kinetic energy of rotation. How do you account for this increase in kinetic energy?

A diver having a moment of inertia of 6.0 kg-m^2 about an axis through its centre of mass rotates at an angular speed of 2 rad/s about this axis. If he folds his hands and feet to decrease the moment of inertia to 5.0 kg-m^2 what will be the new angular speed?

Suppose the platform of the previous problem is brought to rest with the ball in tehhad of the kid standin on the rim. The kid throuws the ball horizontaly to his friend in a direction tangentiasl to the rim with a speed v as seen by his friend. Find the angular velocity wilth which the platform will start rotating.

A boy is standing on a platform which is free to rotate about its axis. the boys holds an open umbrella in his hand. The axis of the umbrella coincides with tht of the platform. The moment of inertias of the platform plus the boy sytem is 3.0xx10^-3 kg-m^ and that of the umbrella is 2.0xx10^-3 kg-m^2 . The boy starts spinning the umbrella about the axis at an angular speed of 2 rev s1 with respect to himself . Find the angular velocity imparted to the platform.

Ganesh is a champion in cricket in his school. When he is in the ground (for practice) and he used to whirl his bat in different style. His coach was Mr. Gunalan. The coach asked Ganesh to hold the bat at its handle and roatate fastly. But Ganesh could not do as his coach said, Ganesh developed pain in his hands. Then his coach told him to rotate the bat by holding it at its mid point. When Ganesh rotated at this position, he was able to rotate the bat faster. Ganesh was surprised and asked his coach how. (i) What was coach's explanation to Ganesh ? (ii) What is Radius of Gyration ? Give an example. (iii) How moment of Inertia is related with Angular velocity ?

A man stands before a large wall at a distance of 50.0 m and claps his hands at regular intervals. Initially, the interval is large. He gradually reduces the interval and fixes it at a value when the echo of a clap merges with the next clap. If he has to clap 10 times during every 3 seconds, find the velocity of sound in air.