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Unformatted text preview: Oregon State University Physics 201 Final Exam Fall Term, 2008 Form A General directions : Only one sheet of paper (8.5 x 11both sides), with only handwritten notes, may be used during this exam. You may use any kind of calculator, provided that it is not part of a PDA, cell phone, palmtop or laptopand that it is not transmitting any information wirelessly. Physical constants and other possibly useful information are provided here. Answer Question #1 f rst. Physical constants and other possibly useful information: g = 9.80 m/s 2 Question #1: What is the Form designation (A, B, C, D, E, F or X) for your examshown at the top of this page? Write this letter in the answer box for Question 1 on the rst answer sheet in the exam booklet. For questions 2- 16 : For multiple-choice or true/false items, write the letter of the one best answer in the appropriate box on the answer sheet. For questions requiring short answers (a word or short phrase only), write those in the spaces provided. Youre graded on your answers onlyno need to show work. Assume 3 signi cant digits and SI units in all numeric answers unless instructed otherwise. True/False (10 points each) 2. True or false? A friction force always does work on an object. F 3. True or false? If you push on an ideal spring, it pushes back on you with a force equal in magnitude but op- posite in direction to your pushing force. T 4. True or false? If you hang a mass vertically, at rest, from an ideal spring, there is some (non-zero) spring potential energy in this system. T 5. True or false? A conservative force acting on an object never does work on that object. F 6. True or false? Mechanical energy is conserved when a projectile is falling toward the surface of the moon. T 7. True or false? If you cut a spring in half, you also reduce its stiffness by half n . F Short Answer (10 points each) 8. Express spring potential energy in kg, m, and s. kgm 2 /s 2 9. At the bottom of a swinging pendulums arc, is the centripetal force equal to, less than, or greater than the tension in the pendulum arm? less than 10. A 29 Nm torque acts for 4.00 seconds about the geo- metric center of an object, initially at rest. The ob- jects moment of inertia about that center is 100 kgm 2 . What work does the torque do on the object? 67.3 J 11. Complete this sentence: Total energy is conserved in an isolated (or closed) system . 12. Describe one situation where a gravitational force would act on an object but do no work on the object. The object doesnt move; or it moves perpendicularly to the force. 13. An ideal spring-mass system ( k = 25 N/m; k m = 3.0 kg) is oscillating horizontally on a frictionless surface. At the moment when the spring is neither compressed nor stretched, the masss speed is 4.00 m/s. Find its speed when the spring is compressed by 0.78 m. 3.31 m/s Multiple Choice (10 points each) 14. If a bottle half- lled with water is in static mechanical equilibrium, which of the following must be true?equilibrium, which of the following must be true?...
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- Fall '08