Задача 10390.

A ball attached to a weightless thread rotates in a horizontal plane around a vertical axis with a frequency n1 = 2 rpm. How many times did the kinetic energy of the ball change after the thread was shortened by 2 times, if at the beginning the angular momentum was L1 = 0.3 kg*m^2/s?

A detailed solution with a brief note of the condition, formulas and laws used in the solution, the derivation of the calculation formula and the answer.
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