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A boy stands over the centre of a horizontal platform which is rotating freely with a speed of  about a vertical axis through the centre of the platform and straight up through the boy. He holds  masses in each of his hands close to his body. The combined moment of inertia of the system is . The boy now stretches his arms so as to hold the masses of inertia of the system increases to . The kinetic energy of the system in the latter case as compared with that in the previous case will

a)

Remains unchanged

b)

Decrease

c)

Increase

d)

Remains uncertain


Question ID - 53907 | Toppr Answer

A boy stands over the centre of a horizontal platform which is rotating freely with a speed of  about a vertical axis through the centre of the platform and straight up through the boy. He holds  masses in each of his hands close to his body. The combined moment of inertia of the system is . The boy now stretches his arms so as to hold the masses of inertia of the system increases to . The kinetic energy of the system in the latter case as compared with that in the previous case will

a)

Remains unchanged

b)

Decrease

c)

Increase

d)

Remains uncertain

1 Answer - 5876 Votes

3537

Answer Key : (b) -

(b)

. If boy stretches his arm then moment of inertia increases and accordingly kinetic energy of the system decreases because  constant and



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