Disc 50 kg and 25 cm radius rotates about a fixed axis extending perpendicularly to the plane of the disc through its center, making about 8.0 / sec. The rim disc brake pad pressed with a force of 40 N, under the influence of which the disc stopped after 10 seconds. To determine the coefficient of friction.

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