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Unformatted text preview: schneiter (tcs639) – HW17 – Ross – (89152) 1 This printout should have 12 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 (part 1 of 3) 10.0 points A force vector F = F x ˆ i + F y ˆ j + F z ˆ k acts on a particle located at vector X = ( x, y, z ). Given F x = − 31 N, F y = 7 . 97 N, F z = − 86 . 1 N, x = 8 . 43 m, y = − 3 . 71 m and z = − 8 . 02 m, calculate the three components of the torque vector vector τ = τ x ˆ i + τ y ˆ j + τ z ˆ k . First, calculate the τ x component. Correct answer: 383 . 35 N m. Explanation: The torque vector is defined as the cross product vector τ = vector X × vector F . In components, this means τ x = y F z − z F y = 383 . 35 N m , τ y = z F x − x F z = 974 . 443 N m , τ z = x F y − y F x = − 47 . 8229 N m . 002 (part 2 of 3) 10.0 points Second, calculate the τ y component. Correct answer: 974 . 443 N m. Explanation: See above. 003 (part 3 of 3) 10.0 points Finally, calculate the τ z component. Correct answer: − 47 . 8229 N m. Explanation: See above. 004 (part 1 of 2) 10.0 points A cylinder with moment of inertia 28 . 7 kg m 2 rotates with angular velocity 8 . 01 rad / s on a frictionless vertical axle. A second cylin der, with moment of inertia 26 kg m 2 , initially not rotating, drops onto the first cylinder and remains in contact. Since the surfaces are rough, the two eventually reach the same an gular velocity. I 2 I 1 ω Before ω After Calculate the final angular velocity. Correct answer: 4 . 20269 rad / s. Explanation: From conservation of angular momentum ( I 1 + I 2 ) ω = I 1 ω , or ω = I 1 I 1 + I 2 ω = (28 . 7 kg m 2 ) (28 . 7 kg m 2 ) + (26 kg m 2 ) (8 . 01 rad / s) = 4 . 20269 rad / s ....
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This note was uploaded on 04/23/2009 for the course PHYS 152 taught by Professor Button during the Spring '08 term at IUPUI.
 Spring '08
 BUTTON
 mechanics, Force

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