Name_____________________________Phys 113: Final Exam6/28/2007"An expert is a man who has made all the mistakeswhich can be made in a very narrow field."-Niels BohrWelcome to the Final Exam!Please feel free to ask questions.I will grade these over the weekend and turn in your grades on Monday. I'll contact you about handing them back next week.Enjoy the rest of your summer, especially/even if you are taking 114 next!Here’s the rundown for this exam:Part I: Multiple Choice (True/False) Problems (1-6): 18 points totalPart II: Short Answer / Calculation Problems (7-15): 52 points totalPart III: Calculation Problems (16-19): Choose 2 of the 4 for 30 points total.For Part III, you can do all the problems for extra credit. (But bear in mind that it'll makethe exam take longer...)Part 1: Multiple Choice (True/False) Problems (no partial credit)1. (3 points)An object is moving along with some speed, hence it has some kinetic energy K. Some time later, the object is moving in the opposite direction with three times its initial speed. What is the kinetic energy now? some time some time latera) Kb) 3Kc) -3Kd) 9Ke) -9K2. (3 points)A disk is free to rotate about an axis. A force applied a distance d from the axis causes an angular acceleration α. What angular acceleration is produced if the same force is applied a distance 2d from the axis?a) α b) 2 α c) α /2d) 4 α e) α /4v 3v3. (3 points)An 80 kg man on ice skates pushes a 40 kg boy also on skates with a force of 100 N. The magnitude of the force exerted by the boy on the man isa) 200 Nb) 100 Nc) 50 Nd) 40 N4. (3 points)Body A has twice the mass and twice the specific heat of body B. If they are supplied with equalamounts of heat, how do the subsequent changes in their temperatures compare?a) TA=TBb) TA=2TBc) TA= 1/2(TB)d) TA=1/4(TB)5. (3 points)A block of mass m is at rest on a plane inclined at an angle of 30 degrees with the horizontal. Which of the following statements about the force of static friction is true?a) F>mgb) F>mgcos30c) F=mgsin30d) F=mgcos306. (3 points)True or False?a) In simple harmonic motion, the period is proportional to the square of the amplitude.b) In simple harmonic motion, the frequency does not depend on the amplitude.c) If the acceleration of a particle is proportional to the displacement and oppositely directed, the motion is simple harmonic.Part 1I: Short Answer / Calculation Problems (partial credit available)7. (4 points)My sister (who has the same mass as I do) and I are sitting on the floor of a merry-go-round. I am sitting close to the outer edge, and she is sitting close to the center.a) As the merry-go-round rotates, who experiences the larger acceleration, or are they the same? Why?b) What force is responsible for this acceleration?8. (4 points)I stand on a scale in a pool (I don't know why). The scale gives my weight as 300 N, but I know that it really is 637N. Given that the buoyant force on me is the difference between my actual weight and what the scale reads, find the volume of me that is submerged in the water (density = 1g/cm3).9. (4 points)Dean reads in his physics book that when two people pull on the end of a rope in a tug-of-war, the forces exerted by each on the other are equal and opposite, according to Newton’s third law. Misunderstanding the law tragically, Dean runs out to challenge Hugo the Large, convinced that the laws of physics guarantee a tie. Hugo lumbers over, picks up the rope, pulls Dean off his feet, and then drags him through a puddle, across the road, and up the steps of the physics building. Use a force diagram to show Dean that, in spite of Newton’s third law, it is possible forone side to win a tug-of-war.10. (10 points)Water is moving with a speed of 5.0 m/s through a pipe with a cross sectional area of 5.0 cm2. The water gradually descends 10 m as the pipe increased in area to 8.0 cm2.a) What is the speed at the lower level?b) If the pressure at the upper level is 1.5 x 105 Pa, what is the pressure at the lower level?(density of water is 1 g/cm3)11. (10 points)I am taking a shortcut through a playground on my way home from a rock concert, and I see one of those rotating platforms (some people call them merry-go-rounds, but I don't) that are fun to play on. Excited, I run toward the stationary platform and jump on, causing it to begin rotating. If my mass is 65kg, my initial speed was 2m/s, the rotational inertia of the platform is 800 kgm2 and I landed a perpendicular distance of 1m away from the center of the platform (as depicted below):a) what is the angular velocity of the system after I land?b) what is the kinetic energy of the system after I land?2m/s1 m12. (5 points) A physics class is going to make ice cream by using liquid nitrogen to cool it down, but they don't know how much they're going to need. You can help them by figuring out how much heat must be removed from the ice cream mixture to get it to freeze. The mixture, which contains mostly sugar and cream, has a mass of 6 kg, specific heat of 3800 J/kgC, latent heat of 3.3x105 J/kg, and freezing point of 0C. How much heat (measured in Joules) must be removed from this mixture for it to freeze entirely (but remain at the freezing point temperature) if it starts fromroom temperature (20C)?13. (5 points) A mass of 0.6 kg oscillates between two springs: one has a spring constant k1=200 N/m, and the other has a spring constant k2=250 N/m. If the maximum displacement from equilibrium is 2 cmand x=0 at t=0a) find x(t).b) What is x when t = 0.5s?14. (5 points) Many bats use sonar (basically high frequency sound waves) to locate their prey in the dark, or towatch out for possible predators. If a bat emits a sound wave which can be described by the following equation: tsradxmDtxDm)/1088.1()549(sin),(51a) What is the wavelength?b) What is the frequency of this wave?c) What is the speed of sound?15. (5 points) A simplified yo-yo (treat it as a uniform disk: Idisk = 1/2MR2) rolls down its string as you hold the string stationary. If the mass of the yo-yo is 0.7 kg, and the radius is 5cm, what isa) The acceleration?b) The angular acceleration?c) The force of tension in the string?Part 1II: Choose your own adventure! (partial credit available)Choose two of the following four problems, or do three or all four for (up to ten points) extra credit. I'll choose, to your benefit, which one/s will count for extra credit.16.