Angular Acceleration - General Physics - Solved Past Paper, Exams of Physics

Download Angular Acceleration - General Physics - Solved Past Paper and more Exams Physics in PDF only on Docsity! 5. (25 pts) A rotating wheel requires 3 s to rotate 37 revolutions. Its angular speed at the end of the 3 s interval is 98 rad/s. Assume that the angular acceleration of the wheel is constant. a) (5 pts) Through what angle (measured in radians) does the wheel rotate during the 3 s interval? We have the number of revolutions, just convert to angle: 37 rev × 2π rad rev = 232.5 rad b) (10 pts) What was the initial angular speed of the wheel? (Hint: It was not started from rest!) Not being given the angular acceleration, we need an equation without α, θf − θi = (1/2)(ωi + ωf )t 232.5 = (1/2)(ωi + 98)(3) ωi = 57 rad/s c) (5 pts) Calculate the angular acceleration of the wheel. Now that we have the initial velocity, we can use ωf = ωi + αt 98 = 57 + 3α α = 13.7 rad/s 2 Note that all of the kinematics equations involve ωi, so there’s no way around using the value from (b) to solve this. d) (5 pts) If the moment of inertia of the wheel is 25 kg·m2, what is the rotational kinetic energy of the wheel at the end of the 3 s interval? Kr = (1/2)Iω 2 = (1/2)(25)(982) = 120050 J