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# String and Pulley?

A 8 m long string is wrapped around a pulley that is free to rotate about a fixed axle. The pulley has a radius of 6.4 cm and is initially at rest. The thickness and masss of the string are negligible. Someone pulls on the free end of the string with a 20N force, thereby unwinding it and giving the pulley an acceleration of 17 rad/sec2.

1)Through what angle has the pulley rotated when the string is completely unwound?

Δθ =

rad

2)What is final angular velocity of the pulley

ω =

rad/sec

### 1 Answer

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- NCSLv 71 month agoFavourite answer
1) arc length s = r*Θ

8 m = 0.064m * Θ

Θ = 125 radians

2) ω² = ω₀² + 2αΘ = 0² + 2 * 17rad/s² * 125rad = 4250 rad/s²

ω = 65 rad/s

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