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Unformatted text preview: chauhan (mmc2762) – Ch6-H1 – turner – (56910) 1 This print-out should have 21 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 If a golf ball and a ping-pong ball both move with the same kinetic energy, which has the greater speed? 1. Cannot be determined 2. the ping-pong ball correct 3. the golf ball 4. The two balls have the same speed. Explanation: Kinetic energy is 1 2 mv 2 . Since they have the same kinetic energy, 1 2 m g v 2 g = 1 2 m p- p v 2 p- p . Since m g > m p- p , it follows that v g < v p- p . 002 (part 2 of 2) 10.0 points In a gaseous mixture of massive molecules and light molecules with the same average KE, which have the greater speed? 1. Cannot be determined 2. They have the same speed. 3. the light molecules correct 4. the massive molecules Explanation: Since m massive > m light ,v massive < v light . 003 10.0 points Calculate the speed of an 6 . 7 × 10 4 kg airliner with a kinetic energy of 1 . 4 × 10 9 J. Correct answer: 204 . 429 m / s. Explanation: Basic Concept: KE = 1 2 mv 2 Given: m = 6 . 7 × 10 4 kg KE = 1 . 4 × 10 9 J Solution: The speed of the airliner with a given kinetic energy is v = radicalbigg 2 K m = radicalBigg 2(1 . 4 × 10 9 J) 67000 kg = 204 . 429 m / s 004 10.0 points Two marbles, one twice as massive as the other, are dropped from the same height. When they strike the ground, how does the kinetic energy of the more massive marble compare to that of the other marble? 1. It has the same KE. 2. It has one-half the KE. 3. It has twice the KE. correct 4. It has 4 times the KE. Explanation: KE = 1 / 2 mv 2 The two marbles experience the same ac- celeration while falling and so hit the ground with the same velocity. Therefore the mar- ble with twice the mass has twice the kinetic energy. 005 10.0 points Suppose an automobile has an initial kinetic energy of 2300 J. If it increases its speed by six times, what will be its kinetic energy? Correct answer: 82800 J. Explanation: chauhan (mmc2762) – Ch6-H1 – turner – (56910) 2 Let KE i = 2300 J and n = 6 ....
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This note was uploaded on 04/03/2012 for the course PHYSICS 303K taught by Professor Antoniewicz during the Spring '11 term at University of Texas.
- Spring '11