qz6sol_6839sp10 - a What is the angular acceleration of the...

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TA: Tomoyuki Nakayama Tuesday, March 2 nd , 2010 PHY 2048: Physic 1, Discussion Section 6839 Quiz 6 (Homework Set # 8) Name: UFID: Formula sheets are not allowed. Calculators are allowed. Do not store equations in your calculator. You need to show all of your work for full credit. ________________________________________________________________________________ The figure below right shows a uniform disk that can rotate around its center like a merry-go round. The disk has a radius of 5.00 cm and a mass of 80.0 grams and is initially at rest. Starting at time t = 0, two forces are to be applied tangentially to the rim as indicated, so that at time t = 2.00 s the disk has an angular velocity of 200 rad/s counterclockwise. Force F 2 has a magnitude of 0.300 N.
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Unformatted text preview: a) What is the angular acceleration of the disk during the time interval between t = 0 and t = 2 s? Angular acceleration is given by the change in angular velocity divided by time interval. We take positive direction counterclockwise. The angular acceleration is α = Δω/Δt = (200 - 0)/(2 - 0) = 100 rad/s 2 b) What is the angular displacement during the time interval? We use the kinematic equation for angular displacement. We get Δθ = (1/2)αΔt 2 = 200 rad c) What is the magnitude of F 1 ? We apply Newton’s 2 nd law in angular form to the disk and solve it for the unknown force F 1 . Iα = F 2 R – F 1 R F ⇒ 1 = F 2 – Iα/R = 0.100 N, where I = (1/2)MR 2 = 1.00 × 10-4 kg m 2...
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This note was uploaded on 01/15/2012 for the course PHY 2048 taught by Professor Field during the Fall '08 term at University of Florida.

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