HW5 Solution

# HW5 Solution - lew (dl9564) hk5 Opyrchal (41104) 1 This...

This preview shows pages 1–2. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: lew (dl9564) hk5 Opyrchal (41104) 1 This print-out should have 6 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 2) 10.0 points A thin uniform cylindrical turntable of radius 2 . 9 m and mass 23 kg rotates in a horizontal plane with an initial angular speed of 11 rad / s. The turntable bearing is frictionless. A clump of clay of mass 9 . 7 kg is dropped onto the turntable and sticks at a point 1 . 7 m from the point of rotation. Find the angular speed of the clay and turntable. Correct answer: 8 . 52811 rad / s. Explanation: Let : R = 2 . 9 m , M = 23 kg , = 11 rad / s , and m = 9 . 7 kg . Basic Concepts: summationdisplay vector L = dvector ext dt K = K f- K i = Q . From conservation of the angular momentum it follows that L i = L f or I i = I f f , where I i = 1 2 M R 2 = 1 2 (23 kg) (2 . 9 m) 2 = 96 . 715 kg m 2 . Similarly, I f = I i + mx 2 = 96 . 715 kg m 2 + (9 . 7 kg) (1 . 7 m) 2 = 124 . 748 kg m 2 . Finally, f = I i I f = (96 . 715 kg m 2 ) (124 . 748 kg m 2 ) (11 rad / s) = 8 . 52811 rad / s . 002 (part 2 of 2) 10.0 points Calculate the loss of energy to thermal en- ergy. Correct answer: 1314 . 88. Explanation: K i = 1 2 I i 2 = 1 2 (96 . 715 kg m 2 ) (11 rad / s) 2 = 5851 . 26 J . K f = 1 2 I f 2 f = 1 2 (124 . 748 kg m 2 ) (8 . 52811 rad / s) 2 = 4536 . 38 J . Therefore, K = K f- K i = (4536 . 38 J)- (5851 . 26 J) =- 1314 . 88 J . Since the question asks for the loss of energy, we take the negative of this number. 003 10.0 points A solid cylinder of mass M = 11 kg, radius R = 0 . 43 m and uniform density is pivoted on a frictionless axle coaxial with its symmetry axis. A particle of mass m = 3 kg and initial...
View Full Document

## HW5 Solution - lew (dl9564) hk5 Opyrchal (41104) 1 This...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online