Home
Class 11
PHYSICS
A man, sitting firmly over a rotating st...

A man, sitting firmly over a rotating stool has his arms streched. If he folds his arms, the work done by the man is.

A

zero

B

positive

C

negative

D

may be positive or negative

Text Solution

Verified by Experts

The correct Answer is:
B
`KE = (L^(2))/(2I)` since by folding arm moment of inertia decreases while angular momentum remain constant. So `KE` will increases therefore work done by the man is positive.
Doubtnut Promotions Banner Mobile Dark
|

Similar Questions

Explore conceptually related problems

A person is standing on a rotating platform, with his arms at his sides. If he stretches his arms, then which of the following statements is correct?

A preson is standing on the centre of a rotating table with his arms outstretched. The table is rotating freely with an angular his hands towards his chest. The moment of inertia reduces to (3)/(5) time the original moment of inertia. Calculate angular speed of the man when he withdraws his hands.

Knowledge Check

  • A person sitting firmly over a rotating stool has his arms stretched. If he folds his arms, his angular momentum about the axis of rotation

    A
    increases
    B
    decreases
    C
    remains unchanged
    D
    doubles

  • 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
    increase
    B
    decrease
    C
    become zero
    D
    remain constant

  • A gymnast standing on a rotating stool with his arms outstretched, suddenly lowers his arms

    A
    his angular velocity decreases
    B
    his angular velocity increases
    C
    his moment of inertia remains same
    D
    his moment of inertia increases

    • Similar Questions

    Explore conceptually related problems

    A man stands on a rotating platform, with his arms stretched horizontal holding a 5 kg weight in each hand. The angular speed of the platform is 30 revolutions per minute. The man then brings his arms close to his body with the distance of each weight from the axis changing from 90 cm to 20 cm . moment of inertia of the man together with the platform may be taken to be constant and equal t 7.6 kg m^(2) . (a) What is the his new angular speed ? (Neglect friction.) (b) Is kinetic energy conserved in the process ? If not, from where does the change come about ?

    If a gymnast sitting on a rotating disc with his arms out stretched suddenly lower his arms, then

    If a gymnast ,standing on a rotating stool with his arms ant stretched ,suddenly ,owers his arms

    If a person sitting on a rotating stool with his hands outstretched, suddenly lowers his hands, then his

    A man stands on a rotating platform with his arms stretched holding a 5 kg weight in each hand. The angular speed of the platform is 1.2 rev s^-1 . The moment of inertia of the man together with the platform may be taken to be constant and equal to 6 kg m^2 . If the man brings his arms close to his chest with the distance n each weight from the axis changing from 100 cm to 20 cm . The new angular speed of the platform is.

    Home
    Profile