The speed of a ball falling down in glycerin varies with time according to the law v = vо (1-e ^ -at), where vо = 6.1 cm / s; a = 140 s ^ -1. Determine the density of the ball, if it is known: 1) after t = 0.01 s after the start of the movement, the viscous friction force modulo is 3 times greater than the resultant of all the forces applied to the ball; 2) the density of glycerol is 1.25 * 10 ^ 3 kg / m ^ 3.

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