Question

A boy is standing on a horizontal massless
rotating wheel with his hands stretched. Kinetic
energy of boy is 120 J. If he now folded his hands
then M.I is reduced to 80%. Then a new K.E. of
boy,
(1) Increases by 30 J
(2) Decreases by 30 J
(3) Increases by 20 J
(4) Remains constant​

Answer 1

Answer:

A boy is standing on a horizontal massless rotating wheel with his hands stretched. Kinetic energy of boy is 120 J. If he now folded his hands then M.I is reduced to 80%. Then a new K.E. of boy, Increases by 30 J.

Explanation:

Formula of K.E:

Active vitality is straightforwardly corresponding to the mass of the article and to the square of its speed: K.E. = 1/2 m v2. On the off chance that the mass has units of kilograms and the speed of meters every second, the dynamic vitality has units of kilograms-meters squared every second squared.