Physics

A desk fan has three (approximately) rectangular sheets of 15.8 cm long and 5 cm wide, each with a mass of 140 g. The fan is rotating at a constant angular speed of 19.8 rad / s when the power is turned off. Due to friction the angular velocity of the fan slows down in a uniform manner and after 5.2 s it still runs at 4.30 rad / s.
How many revolutions has the fan performed at this time?

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3. 👁 101
1. {[(19.8 + 4.30) / 2] * 5.2} / π

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posted by Scott
2. Thx

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posted by Bob

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