PHYS101 Sec 001 Hour Exam No. 3 Fall 2007 - Prof. Robert Gowdy, Exams of Physics

Download PHYS101 Sec 001 Hour Exam No. 3 Fall 2007 - Prof. Robert Gowdy and more Exams Physics in PDF only on Docsity! PHYS101 Sec 001 Hour Exam No. 3 Page: 1 PHYS101 Sec 001 Hour Exam No. 3 Page: 2 1 The rst demonstration of electromagnetic wave generation used a. rapid mechanical switches. b. charged mechanical rotors. c. vacuum tube oscillators. d. electric sparks in air. 2 In comparison to Kepler's Laws of Planetary Motion, Newton's theory of Universal Gravitation predicted a. almost the same motions but with corrections. b. a completely different set of motions. c. exactly the same motions. d. the same motions interpreted differently. 3 If the speed of an automobile increases by a factor of two, the distance that it takes to stop should increase by a factor of a. 4. b. 3. c. 2: d. 9. e. 16: 4 The following spacetime diagram uses c=1 units. Which is the world-line of an object at rest? 5 An electrical power plant a. creates energy. b. converts energy. c. destroys energy. 6 In one experiment, two spheres, one with a mass of 1kg and the other with a mass of 1000kg are separated by one meter and attract each other with a tiny force. If the spheres are then replaced by one with a mass of 3kg and one with a mass of 2000kg, still one meter apart, the force between the masses will be a. the same as in the rst experiment. b. twice the force in the rst experiment. c. three times the force in the rst experiment. d. six times the force in the rst experiment. PHYS101 Sec 001 Hour Exam No. 3 Page: 5 17 Suppose that two objects, each with the same mass, are accelerated from rest to the same velocity. The force that accelerates one object is much larger than the force that accelerates the other object but acts for a shorter time. The work done by the larger force is a. smaller than the work done by the smaller force. b. larger than the work done by the smaller force. c. equal to the work done by the smaller force. d. unrelated to the work done by the smaller force. 18 In a spacetime diagram with t the time and x the distance, all of the points on the space axis have a. t = x. b. x = 0. c. t = x = 0. d. t = 0. 19 Lorentz sought to explain the result of the Michelson-Morely experiment by asserting that the aether-wind causes changes in a. the properties of light. b. physical laws. c. time intervals. d. lengths. 20 The Michelson-Morely Experiment tested the predictions of a. Einstein's theory of relativity. b. Maxwell's theory of electromagnetism. c. the Aether theory of light propagation. d. Newton's theory of mechanics. 21 Maxwell's derivation of the speed of light from physical laws was a problem for his fellow scientists because a. It violated energy conservation. b. They disbelieved some steps in the derivation. c. The speed was not what they expected. d. It violated velocity addition. 22 In the aether theory of light, a pulse of light travels at 186,000 miles per second relative to a. the observer of the light. b. the source of the light. c. any inertial reference frame. d. the aether. PHYS101 Sec 001 Hour Exam No. 3 Page: 6 23 The starship Enterprise is travelling on impulse drive at 4/5 light speed. For every two minutes that pass on board the ship, a clock back on earth will read an interval close to a. two minutes. b. three minutes and twenty seconds. c. two minutes and thirty seconds. d. two minutes and ten seconds. 24 Suppose that observers on Earth nd that an asteroid collides with the planet Mars at exactly the same time that a comet collides with the earth. If a spaceship ying from Earth toward Mars observes these catastrophes, it will calculate that a. Earth get hit before Mars does. b. Mars get hit before the earth does. c. both happen at the same time. 25 A spaceship travels from the earth to a star that is 12 light years away. If the trip takes 13 years in earth time, how many years pass on board the ship? a. 4. b. 5. c. 2. d. 3. e. 6. 26 A 2kg rock is dropped from rest at a height of 30 meters above the ground. How much heat energy is generated when it hits the ground? a. 60J. b. 600J. c. 900J. d. 0. 27 The space between the stars is not quite empty. It contains faint traces of gas as well as charged particles. If this interstellar medium were removed, the light from the stars a. would reach us only from stars emitting stellar winds. b. would no longer reach us. c. would still reach us. 28 In the following spacetime diagram, which letter is closest to the event with x = 2, t = 1? PHYS101 Sec 001 Hour Exam No. 3 Page: 7 29 Suppose that a car and a truck are traveling at the same speed. If the truck has three times the mass of the car, then the truck's kinetic energy is a. eight times that of the car. b. nine times that of the car. c. twice that of the car. d. three times that of the car. e. four times that of the car. 30 A pendulum consists of a lead ball attached to one end of a string that is 1:25m long. The other end of the string is attached to a hook xed in the ceiling. The pendulum is started by lifting the ball until the string is horizontal and the ball is against the ceiling. Which of the following answers is closest to the speed of the ball when it gets to the low point of its swing? a. 8m/s. b. 5m/s. c. 6m/s. d. 25m/s. e. 3:5m/s. 31 Which of the following phenomena consist of electromagnetic waves travelling at the speed of light? a. gamma radiation b. gravity waves. c. alpha rays. d. beta rays. 32 The force on a 5kg object in a gravitational eld whose magnitude is 4m/s2 is equal to a. 6N. b. 4N. c. 50N. d. 20N. e. 5N.