rotational mechanics

if a girl stands on a rotating platform and then suddenly if she getz her hands inwards towardz her then

angularmomentum increases
angular velocity decreases
moment of inertia decreases
moment of inertia increses

wch of the following statement(z) is/are true yy???

6 Answers

11
Khyati ·

Moment of inertia decreases because since she takes her hands inwards, r is decreasing (r = radius) [ I = Mr2]

Angular velocity increases because angular velocity is inversely proportional to radius.(ω = v/r)

Angular momentum decreases because it is directly proportional to radius.(L = r x P )

1
Euclid ·

in this case angular momentum L is conserved (no external torque)..

so L = constt. => Iω = constt.

also I decreases as distance of points from axis decreases which implies angular velocity ω increases.

1
harsha121 ·

so the answer is only option c????

106
Asish Mahapatra ·

yes :)

11
Khyati ·

Oh sorry sorry, I made a silly mistake, just forgot ki angular momentum will remain constant.(I know I shouldn't have, its a very important concept).

Yeah so the answer is only the option (c)

And thanks Euclid for your correct answer. [1]

6
AKHIL ·

the correct ans is C....

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