Physics Test3 Solutions

# Physics Test3 Solutions - quiz 03 – VENNES, ROSS – Due:...

This preview shows pages 1–3. 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: quiz 03 – VENNES, ROSS – Due: Nov 14 2007, 10:00 pm 1 Question 1, chap 9, sect 1. part 1 of 1 10 points Given: G = 6 . 673 × 10 − 11 N m 2 / kg 2 Two balls, each with a mass of 0.885 kg, exert a gravitational force of 8 . 30 × 10 − 11 N on each other. How far apart are the balls? 1. . 66031 m 2. . 6809 m 3. . 702014 m 4. . 723889 m 5. . 746456 m 6. . 769596 m 7. . 793533 m correct Explanation: Basic Concept: F g = G m 1 m 2 r 2 Given: m 1 = m 2 = 0 . 885 kg F g = 8 . 30 × 10 − 11 N G = 6 . 673 × 10 − 11 N · m 2 kg 2 Solution: r 2 = Gm 1 m 2 F g = parenleftBig 6 . 673 × 10 − 11 N · m 2 kg 2 parenrightBig (0 . 885 kg) 2 8 . 3 × 10 − 11 N = 0 . 629694 m 2 Thus r = √ . 629694 m 2 = 0 . 793533 m Question 2, chap 12, sect 5. part 1 of 2 10 points A wheel is formed from a hoop and four equally spaced spokes. The hoop’s radius is the length of each spoke. . 062 kg 1 . 7 kg . 71 m There are four equally spaced spokes. Each spoke has mass 0 . 062 kg. The hoop’s mass is 1 . 7 kg. The hoop’s radius is 0 . 71 m. Determine the moment of inertia of the wheel about an axis through its center and perpendicular to the plane of the wheel. 1. . 898642 kg m 2 correct 2. . 928128 kg m 2 3. . 957917 kg m 2 4. . 988384 kg m 2 5. 1 . 0235 kg m 2 6. 1 . 05601 kg m 2 7. 1 . 09156 kg m 2 8. 1 . 12826 kg m 2 9. 1 . 16531 kg m 2 10. 1 . 22513 kg m 2 Explanation: Let : n = 4 spokes , m = 0 . 062 kg , M = 1 . 7 kg , and R = 0 . 71 m . Each spoke contributes to the total moment of inertia as a thin rod pivoted at one end, hence I = M R 2 + n mR 2 3 = bracketleftBig M + n m 3 bracketrightBig R 2 = bracketleftbigg (1 . 7 kg) + 4 (0 . 062 kg) 3 bracketrightbigg (0 . 71 m) 2 = 0 . 898642 kg m 2 . Question 3, chap 12, sect 5. part 2 of 2 10 points quiz 03 – VENNES, ROSS – Due: Nov 14 2007, 10:00 pm 2 Determine the moment of inertia of the wheel about an axis through its rim and per- pendicular to the plane of the wheel. 1. 1 . 53732 kg m 2 2. 1 . 58682 kg m 2 3. 1 . 63821 kg m 2 4. 1 . 69714 kg m 2 5. 1 . 75496 kg m 2 6. 1 . 81539 kg m 2 7. 1 . 88063 kg m 2 correct 8. 1 . 94568 kg m 2 9. 2 . 01144 kg m 2 10. 2 . 07368 kg m 2 Explanation: From the parallel axis theorem I rim = I + ( M + n m ) R 2 = (0 . 898642 kg m 2 ) + [(1 . 7 kg) + 4 (0 . 062 kg)] (0 . 71 m) 2 = 1 . 88063 kg m 2 . Question 4, chap 10, sect 2. part 1 of 1 10 points Pat builds a track for his model car out of wood. The track is 4 cm wide (along the z coordinate), 1 m high (along the y coordi- nate) and 3 . 4 m long (along the x coordinate starting from x = 0). The runway is cut such that it forms part of the left-hand side of a parabola, see figure below. x 1m y 3 . 4 m y = 1 (11 . 56 m) [ x − (3 . 4 m)] 2 4 cm Locate the horizontal position of the center of gravity of this track....
View Full Document

## This homework help was uploaded on 04/18/2008 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas at Austin.

### Page1 / 13

Physics Test3 Solutions - quiz 03 – VENNES, ROSS – Due:...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online