oldquiz 3 answers - Overton, Mays Oldquiz 3 Due: Mar 8...

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Overton, Mays – Oldquiz 3 – Due: Mar 8 2005, noon – Inst: Turner 1 This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. The due time is Central time. 001 (part 1 oF 2) 10 points A 48 . 5 kg girl is standing on a 228 kg plank. The plank, originally at rest, is Free to slide on a Frozen lake, which is a ±at, Frictionless sup- porting surFace. The girl begins to walk along the plank at a constant speed oF 1 . 93 m / s to the right relative to the plank. What is her velocity relative to the ice sur- Face? Correct answer: 1 . 59146 m / s. Explanation: v g = velocity oF girl relative to ice v p = velocity oF plank relative to ice v gp = relative velocity oF girl. Let : m g = 48 . 5 kg , m p = 228 kg , and v gp = 1 . 93 m / s . By conservation oF momentum 0 = m g v g + m p v p , v p = - m g v g m p The relative velocity is v gp = v g - v p (1) = v g - µ - m g v g m p = v g m p + m g v g m p = v g ( m p + m g ) m p . Thus v g = m p v gp m g + m p = (228 kg) (1 . 93 m / s) 228 kg + 48 . 5 kg = 1 . 59146 m / s . 002 (part 2 oF 2) 10 points What is the velocity oF the plank relative to the ice surFace? Correct answer: - 0 . 338535 m / s. Explanation: Using Eq. (1), v p = v g - v gp = 1 . 59146 m / s - 1 . 93 m / s = - 0 . 338535 m / s , directed opposite to the girl’s direction. 003 (part 1 oF 1) 10 points Which oF the Following quantities are con- served in an elastic collision but are not con- served in an inelastic collision? 1. kinetic energy correct 2. angular momentum 3. linear and angular momentum 4. kinetic energy and linear momentum 5. total mass 6. None (the same quantities are conserved For both types oF collisions). 7. kinetic energy and angular momentum 8. linear momentum Explanation: In both collisions, the linear and angular momenta are conserved, as well as mass. An elastic collision is defned as a collision where kinetic energy is conserved, which is di²erent From an inelastic collision. 004 (part 1 oF 2) 10 points A(n) 589 kg mass is sliding on a horizontal Frictionless surFace with a speed oF 11 m / s when it collides with a 87 kg mass initially at rest, as shown in the fgure. The masses stick
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Overton, Mays – Oldquiz 3 – Due: Mar 8 2005, noon – Inst: Turner 2 together and slide up a frictionless track at 60 from horizontal. The acceleration of gravity is 9 . 8 m / s 2 . 589 kg 87 kg 9 . 8m / s 2 11 m / s 60 What is the speed of the two blocks imme- diately after the collision? Correct answer: 9 . 58432 m / s. Explanation: Let : v 12 = speed of blocks after collision m 1 = 589 kg , m 2 = 87 kg , v 1 = 11 m / s , and g = 9 . 8 m / s 2 . The initial momentum of block 1 is m 1 v 1 . When
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oldquiz 3 answers - Overton, Mays Oldquiz 3 Due: Mar 8...

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