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Physics 2A Practice Final Exam I don’t have the answers yet but will work them out before class on Tuesday. Given my tight time schedule now it’s probably a good idea to come to Tuesday’s class if you want to make sure to get the answers since I don’t know if I’ll have time to go back and edit and replace the file. I’ll keep regular office hours through Wednesday. I have tons of meetings and research to catch up on after Wednesday but if you want to see me Thursday or Friday email or call to make an appointment. The formula sheet as usual is an approximation of the one that you will have for the final. Good luck studying for finals 1. A cylinder has a moment of inertia of ½ MR2. If this cylinder is rolling without slipping along a level surface with a linear speed v, what is the ratio of its rotational kinetic energy to its linear kinetic energy? Remember v=ωR. (C) a. 1/l0 b. 1/5 c. 1/2 d. 1/1 e. 1/20 2. A 2 500-kg truck moving at 10 m/s strikes a car waiting at a traffic light, hooking bumpers. The two continue to move together at 8 m/s. What was the mass of the struck car? (E) a. 1 740 kg b. 1 550 kg c. 1 200 kg d. 1 070 kg e. 625 kg 3. An automobile driver puts on the brakes and decelerates from 50.0 m/s to zero in 20.0 s. What distance does the car travel? (Hint: First determine the deceleration) (E) a. 150 m b. 196 m c. 336 m d. 392 m e. 500 m 4. An 8.00 kg bowling ball moves at 3.00 m/s. How fast must a 3.00 g Ping-Pong ball move so that the two balls have the same kinetic energy? (C) a. 24.0 m/s b. 72.0 m/s c. 155.0 m/s d. 941.0 m/s e. 441.0 m/s 5. A small ferry boat is 5 m wide and 8 m long. When a loaded truck pulls onto it the boat sinks an additional 4.00 cm into the river. What is the weight of the truck (density of water is 1000 kg/m3) (B) a. 1.60 N b. 15680 N c. 1000 N d. 8000 N e. 4560 N 6. Some gas is contained in a tank of constant volume at a pressure of 10 atm at a temperature of 293 K. If half the gas is withdrawn and the temperature is raised to 393 K what is the new pressure in the tank? (C) a. 10.0 atm b. 15.3 atm c. 6.7 atm d. 3.2 atm e. 1.0 atm 7. A closed 2.0-L container holds 3.0 mol of an ideal gas. If 200 J of heat is added, what is the change in internal energy of the system? (D) a. 0 J b. 100 J c. 150 J d. 200 J e. 600 J 8. One kilogram of 100C water is heated until all the water vaporizes into 100C steam. What is its change in entropy? (For water, Lv = 2.26 106 J/kg) (B) a. 12 100 J/K b. 6 060 J/K c. 3 030 J/K d. 1 220 J/K e. 750 J/K 9. Carly places one end of a steel bar in a Bunsen flame and the other end in an ice cube. By what factor is the rate of heat flow changed when the bar’s cross-sectional area is doubled? (A) a. 2 b. 1/2 c. 4.0 d. 1/4 e. stays the same 10. A 3.00-g lead bullet is traveling at a speed of 240 m/s when it embeds in a wood post. If we assume that half of the kinetic energy of the bullet remains as heat energy with the bullet, what is the increase in temperature of the embedded bullet? (specific heat of lead = 0.030 5 kcal/kgC, 1 kcal = 4 186 J) (A) a. 113C b. 137C c. 226C d. 259C e. 298C 11. A rectangular steel plate with dimensions of 30 cm 25 cm is heated from 20C to 220C. What is its change in area? (Coefficient of linear expansion for steel is 11 106/C.) (C) a. 0.82 cm2 b. 1.65 cm2 c. 3.3 cm2 d. 6.6 cm2 d. 8.7 cm2 12. How deep under the surface of a lake would the pressure be double that at the surface? (1 atm = 1.01 × 105 Pa and the density of water is 1000 kg/ m3) (C) a. 1.00 m b. 9.80 m c. 10.3 m d. 24.1 e. 32.2 m 13. A turntable has a moment of inertia of 3.00 102 kgm2 and spins freely on a frictionless bearing at 25.0 rev/min. A 0.300-kg ball of putty is dropped vertically on the turntable and sticks at a point 0.100 m from the center. By what factor does the angular momentum of the system change after the putty is dropped onto the turntable? (E) a. 0.82 b. 1.50 c. 0.25 d. 1.22 e. 1.00 14. A satellite is in a uniform circular orbit about the Earth at a distance of one Earth radius above the surface. What is the speed of the satellite? (The radius of the Earth is 6.4 106 m, G = 6.67 1011 N m2/kg2 and the mass of the Earth is 6.0 1024 kg) (C) a. 2 800 m/s b. 4 200 m/s c. 5 600 m/s d. 16 800 m/s e. 25 000 m/s 15. A 0.30-m-radius automobile tire rotates how many rad after starting from rest and accelerating at a constant 2.0 rad/s2 over a 5.0-s interval? (B) a. 12.5 rad b. 25 rad c. 2.0 rad d. 0.50 rad e. 4.3 rad 16. A billiard ball collides in an elastic head-on collision with a second identical ball. What is the kinetic energy of the system after the collision compared to that before collision? (E) a. the same b. one fourth c. twice d. four times e. not enough information 17. A 7.00-kg bowling ball falls from a 2.00-m shelf. Just before hitting the floor, what will be its kinetic energy? (g = 9.80 m/s2 and assume air resistance is negligible.) (D) a. 14.0 J b. 19.6 J c. 29.4 J d. 137 J e. 56.2 J 18. If we know an object is moving at constant velocity, we may assume: (A) a. The net force acting on the object is zero. b. There are no forces acting on the object. c. The object is accelerating. d. The object is losing mass. e. none of the above 19. A horizontal force of 750 N is needed to overcome the force of static friction between a level floor and a 250-kg crate. If g = 9.8 m/s2, what is the coefficient of static friction? (D) a. 3.0 b. 0.15 c. 0.28 d. 0.31 e. 0.43 20. A ball is rolled horizontally off a table with an initial speed of 0.24 m/s. A stop watch measures the ball’s trajectory time from table to the floor to be 0.30 s. How far away from the table does the ball land? (g = 9.8 m/s2 and air resistance is negligible) (B) a. 0.055 m b. 0.072 m c. 1.2 m d. 1.9 m e. 0.8 m

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posted: | 5/13/2011 |

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