Задача 40694.

Point isotropic source of the sound is on the perpendicular to the plane of the ring, passing through its center O. The distance between the point O and the source of 1.00 m, the ring radius R = 0,50 m. Find the average energy flow through the area bounded by the ring if the point About the sound intensity of 30 mW / m ^ 2.

Detailed solution with the formulas and the laws used in the decision, the withdrawal of the calculation formula and the response.
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