*78. A rider on a mountain bike is traveling to the left in the figure. Eachwheel has an angular velocity of +21.7 rad/s, where, as usual, the plussign indicates that the wheel is rotating in the counterclockwise direc-tion. (a) To pass another cyclist, the rider pumps harder, and the angularvelocity of the wheels increases from +21.7 to +28.5 rad/s in a time of3.50 s. (b) After passing the cyclist, the rider begins to coast, and theangular velocity of the wheels decreases from +28.5 to +15.3 rad/sin a time of 10.7 s. Concepts: (i) Is the angular acceleration positive ornegative when the rider is passing the cyclist and the angular speed(a) Angular speedincreasing(b) Angular speeddecreasingProblem 78of the wheels is increasing? (ii) Is the angular acceleration positive ornegative when the rider is coasting and the angular speed of the wheelsis decreasing? Calculations: In both instances, (a) and (b), determine themagnitude and direction of the angular acceleration (assumed constant)of the wheels.

Given: initial angular velocity = 21.7 m/s final angular velocity = 28.5 rad/s time = 3.50 seconds…

Answered: *78. A rider on a mountain bike is…

Physics for Scientists and Engineers: Foundations and Connections

1st Edition

ISBN:9781133939146

Author:Katz, Debora M.

Publisher:Katz, Debora M.

Chapter12: Rotation I: Kinematics And Dynamics

Section: Chapter Questions

Problem 12PQ

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