C9_presentation

# C9_presentation - dr R d If is measured in radians then dr...

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dr R If θ is measured in radians, then dr = R dθ Divide by the time interval dt: dr/dt = R dθ/dt v = R ω This is true only if ω is expressed in radians! ω = “angular speed”; v = “rotational speed” or just “speed”

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R = 24 cm ω B A A rotating fan turns counterclockwise at a constant angular speed ω of 6.0 rad/s. Point A at the tip of one of the fan blades is at a distance R = 24 cm from the rotation axis of the fan. Point B on the same fan blade is located at a distance R /3 = 8 cm from the rotation axis. (A) At point A, draw an arrow, labeled by V indicating the direction of the velocity of point A. Then do the same for point B. (B) What is the rotational speed of point A? m/s 1.44 rad/s) m)(6.0 (0.24 = = = ϖ r v (C) What is the rotational speed of point B? m/s 0.48 rad/s) m)(6.0 (0.08 = = = ϖ r v What is the direction of the angular velocity of the fan?
(C9T.4) A bicyclist passes in front of you, moving perpendicularly to your line of sight from your left to your right. The angular velocity of the bike’s wheels point roughly (A) to your right. (B) to your left. (C) toward you. (D) away from you. (E) to your right at the top, to your left at the bottom. (F) other.

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## This note was uploaded on 04/17/2008 for the course PHYS 120 taught by Professor Decarlo during the Spring '08 term at DePauw.

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C9_presentation - dr R d If is measured in radians then dr...

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