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# solution_pdf - chaney(glc568 – Work Energy Impulse and...

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Unformatted text preview: chaney (glc568) – Work, Energy, Impulse, and Momentum – murthy – (21118) 1 This print-out should have 49 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 Consider the following systems: I) water behind a dam; II) a swinging pendulum; III) an apple on an apple tree; IV) the space shuttle in orbit. In which of the systems is potential energy present? 1. I, II and III 2. I, II, III and IV correct 3. I and II 4. II, III and IV 5. II and IV Explanation: All the systems have potential energy. 002 (part 2 of 2) 10.0 points In which of the systems is kinetic energy present? 1. II, III and IV 2. II and IV correct 3. I, II, III and IV 4. I, II and III 5. I and II Explanation: Moving objects have kinetic energy. 003 10.0 points Two cars are lifted to the same elevation in a service station. If one car is twice as massive as the other, how do their potential energies compare? 1. They have the same potential energies since they are lifted to the same elevation. 2. The car which is twice as massive as the other will have twice potential energy. correct 3. Unable to determine 4. The car which is twice as massive as the other will have one half potential energy than the other car. Explanation: Potential energy is proportional to the height multiplied by the mass, so the car which is twice as massive as the other will have twice potential energy than the other for a given height. 004 (part 1 of 3) 10.0 points A 42.0 kg child is in a swing that is attached to ropes 1.70 m long. The acceleration of gravity is 9 . 81 m / s 2 . Find the gravitational potential energy as- sociated with the child relative to the child’s lowest position under the following condi- tions: a) when the ropes are horizontal. Correct answer: 700 . 434 J. Explanation: Basic Concept: U g = mgh Given: ℓ = 1 . 70 m m = 42 . 0 kg g = 9 . 81 m / s 2 Solution: The child is at a height h 1 = ℓ from the lowest point, so U g = mgh 1 = (42 kg)(9 . 81 m / s 2 )(1 . 7 m) = 700 . 434 J 005 (part 2 of 3) 10.0 points chaney (glc568) – Work, Energy, Impulse, and Momentum – murthy – (21118) 2 b) when the ropes make a 30 . ◦ angle with the vertical. Correct answer: 93 . 8404 J. Explanation: Given: θ = 30 . ◦ Solution: The child is a distance ℓ cos θ from the at- tachment point, so h 2 = ℓ − ℓ cos θ and U g = mgh 2 = mgℓ (1 − cos θ ) = (42 kg)(9 . 81 m / s 2 )(1 . 7 m) · (1 − cos 30 ◦ ) = 93 . 8404 J 006 (part 3 of 3) 10.0 points c) at the bottom of the circular arc. Correct answer: 0 J. Explanation: Solution: The child is at the lowest point, so h 3 = 0, and U g = mgh 3 = (42 kg)(9 . 81 m / s 2 )(0 m) = 0 J 007 10.0 points Water flows over a section of Niagara Falls at a rate of 1 . 4 × 10 6 kg / s and falls 61 m....
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solution_pdf - chaney(glc568 – Work Energy Impulse and...

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