solution_pdf - Patel (sap785) homework #2 shubeita (58645)...

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Patel (sap785) – homework #2 – shubeita – (58645) 1 This print-out should have 19 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points Despite a very strong wind, a tennis player manages to hit a tennis ball with her racquet so that the ball passes over the net and lands in her opponent’s court. Consider the Following Forces: 1. A downward Force oF gravity, 2. A Force by the hit, and 3. A Force exerted by the air. Which oF the above Forces is (are) acting on the tennis ball aFter it has leFt contact with the racquet and beFore it touches the ground? 1. 1 only. 2. 2 and 3. 3. 1, 2, and 3. 4. 1 and 3. correct 5. 1 and 2. Explanation: The Forces acting on the tennis ball aFter it has leFt contact with the racquet are gravity and air resistance. A Force by the hit is no longer acting on the ball. 002 10.0 points An elevator is being liFted up an elevator shaFt at a constant speed by a steel cable as shown in the fgure below. All Frictional e±ects are negligible. steel cable Elevator going up at constant speed In this situation, Forces on the elevator are such that 1. the upward Force by the cable is equal to the downward Force oF gravity. correct 2. the upward Force by the cable is smaller than the downward Force oF gravity. 3. the upward Force by the cable is greater than the downward Force oF gravity. 4. the upward Force by the cable is greater than the sum oF the downward Force oF gravity and a downward Force due to the air. 5. None oF these. (The elevator goes up because the cable is being shortened, not be- cause an upward Force is exerted on the eleva- tor by the cable.) Explanation: Since the elevator is being liFted at a con- stant speed, the net Force on it is zero, there- Fore, the upward Force by the cable is equal to the downward Force oF gravity. 003 10.0 points Two identical spring-loaded dart guns are si- multaneously fred straight Forward. One fres a regular dart; the other a weighted dart.
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Patel (sap785) – homework #2 – shubeita – (58645) 2 Which dart goes farther? 1. The weighted dart. 2. The regular dart. correct 3. It’s a tie. Explanation: The springs in both guns apply the same amount of force to the darts, but the regular dart has less inertia and therefore has greater acceleration in the gun. So the regular dart emerges with a greater speed and wins the race. Fire the darts horizontally and you will easily see the lighter one goes farther and faster! 004 (part 1 of 3) 10.0 points Two forces, 444 N at 9 and 392 N at 29 are applied to a car in an e±ort to accelerate it. 3587 kg 444 N 9 392 N 29 What is the magnitude of the resultant of these two forces? Correct answer: 790
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This note was uploaded on 04/16/2010 for the course PHY 317k taught by Professor Kopp during the Spring '07 term at University of Texas at Austin.

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solution_pdf - Patel (sap785) homework #2 shubeita (58645)...

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