Seat # Your exam is form 1. Physics P201 D. Baxter/R. Heinz EXAM #3 November 21, 2002 7:00 9:00 PM INSTRUTIONS 1. Please indicate which form (1, 2, 3, or 4) exam you have by marking the appropriate bubble in column P of the SPEIAL ODES box on your answer sheet. Your exam is form 1. 2. Sit in SEAT # given above. 3. DO NOT OPEN THE EXAM UNTIL YOU ARE TOLD TO DO SO. 4. Print your name (last name first) and blacken in the letters on the answer sheet with a #2 pencil.. Print your student number (identification number) and blacken in the numbers on the answer sheet with a #2 pencil. 6. Use the fronts and backs of the question sheets for scratch work. Do not use any other scratch sheets. 7. This is a multiple choice exam. Blacken in the answer to each question on the answer sheet. Fill in one and only one answer to each question. 8. Keep your eyes on your own work. 9. You have two hours to complete the exam. When you finish, please show your picture ID as you turn in your answer sheet. Please leave quietly so others are not disturbed. 10. THERE ARE 24 QUESTIONS PLEASE ANSWER ALL OF THEM. THERE IS NO PENALTY FOR GUESSING! This is a closed book, closed note exam! You may use only a calculator and three self-prepared sheets of formulas.
1. A ventilation fan has a net torque of 4.2 N m applied to it. Its angular acceleration is 7.9 rad/ s 2. What is its moment of inertia? a. 63 kg m 2 b..3 kg m 2 c..43 kg m 2 d..33 kg m 2 e..23 kg m 2 2 and 3. A bowling ball of mass 3.0 kg is attached to the end of a 6.0 m long bar which has a mass of 2.0 kg. The other end of the bar is hinged at the wall. A vertical string from the bowling ball to the ceiling supports the bar-ball system. string hinge Bar Ball 2. What is the tension in the string? a. 24. N b. 29.4 N c. 34.3 N d. 39.2 N e. 44.1 N 3. What is the moment of inertia of the bar-bell system with respect to an axis through the hinge and perpendicular to the page? Treat the ball as a point mass. a. 12 kg m 2 b. 142 kg m 2 c. 132 kg m 2 d. 122 kg m 2 e. 112 kg m 2
4. Two hoops and two spheres, all set side-by-side, are released from rest at the same time and roll without slipping down an inclined plane towards a wall at the bottom. There is no energy loss due to friction. Hoop 1 has a larger mass than hoop 2. Sphere 1 has the same mass as hoop 1. Sphere 2 has the same mass as hoop 2. Which two objects reach the bottom first? a. sphere 1 and sphere 2 b. sphere 1 and hoop 1 c. sphere 2 and hoop 1 d. sphere 2 and hoop 2 e. hoop 1 and hoop 2. The left end of a massless bar is attached to a vertical wall by a hinge. A rope 4.0 m long, attached to this wall at a point 3.0 m above the hinge, extends 4.0 m horizontally, then is attached to the right end of the bar. Another rope, hanging vertically, is also attached to the right end of the bar and supports a 2400 N load. What is the tension in the horizontal rope? 4.0 m hinge Bar 2400 N 3.0 m a. 1600 N b. 2000 N c. 2400 N d. 2800 N e. 3200 N 6. The approximate inside diameter of the aorta in a small mammal is 0.10 cm; that of a capillary is 10 µ m. The average blood flow speed is approximately 0. m/s in the aorta and 1.0 cm/s in the capillaries. If all the blood in the aorta eventually flows through the capillaries, estimate the number of capillaries in the circulatory system. a. 00 b. 20,000 c. 100,000 d. 00,000 e. 7,00,000
7. A hoop that has a mass of.20 kg and a radius of 2 cm. It rolls without slipping along level ground at.00 m/s. Its total kinetic energy is: a. 3.0 J b. 4.0 J c..0 J d. 6.0 J e. 7.0 J 8. A man, with his arms at his sides, is spinning on a light frictionless turntable. When he extends his arms: a. his angular velocity increases b. his angular velocity remains the same c. his rotational inertia decreases d. his rotational kinetic energy increases e. his angular momentum remains the same 9. A body is in equilibrium under the combined action of several forces. Then: a. all the forces must be applied at the same point b the sum of the torques about any point must equal zero c. any two of these forces must be balanced by a third force d. all of the forces are composed of pairs of equal and opposite forces e. the lines of action of all the forces must pass through the center of gravity of the body. 10. Blaise Pascal duplicated Torricelli s barometer using a red Bordeaux wine, of density 984 kg/m 3, as the working liquid (see figure below). What was the height h of the wine column for normal atmospheric pressure (P o = 101.3 kpa )? (Assume that the absolute pressure in the sealed region above the column of wine is.3 kpa). a..28 m b. 6.31 m c. 7.64 m d. 8.82 m e. 9.96 m
11. Water at absolute pressure of 2.0 10 Pa is flowing at 6.0 m/s in a horizontal pipe at a point where its cross-sectional area is A. What is the pressure and velocity of the water in a different region of the pipe at which its cross-sectional area is 3A? Density of water is 1.0 10 3 kg/m 3. a. 2.2 10 Pa, 12 m/s b. 2.2 10 Pa, 2.0 m/s c. 1.0 10 Pa, 2.0 m/s d. 2. 10 Pa, 0.7 m/s e. 2.0 10 Pa, 0.7 m/s 12. A uniform disc-shaped pulley has a mass m and is free to rotate on a horizontal axis through its center. A rope passes over the pulley and is attached to a mass m 2 on one end and m 1 on the other, where m 2 >m 1. What is the magnitude of the acceleration of the mass. a. 2(m 2 -m 1 )g/(m 1 + m 2 + m) b. (m 2 -m 1 )g/(m 1 + m 2 + m/2) c. (m 2 -m 1 -m)g/(m 1 + m 2 + m/2) d. (m 2 -m 1 +m)g/(m 1 + m 2 + m) e. (m 2 -m 1-2m)g/(m 1 + m 2 + m) 13. The standard kilogram is a platinum-iridium cylinder 39.0 mm in height and 39.0 mm in diameter. What is the density of the material? a. 21. g/cm 3 b. 19.3 g/cm 3 c. 13.6 g/cm 3 d. 10.7 g/cm 3 e. 7.96 g/cm 3 14. A copper wire of length 2 meters, cross sectional area 7.1 10-6 m 2 and Young s modulus 11 10 10 N/ m 2 has a 200 kg load hung on it. What is its increase in length? (Neglect the mass of the copper wire itself.) a. 0.2 mm b. 1.0 mm c. 2. mm d..0 mm e. 10.0 mm
1. Estimate the total mass of the Earth s atmosphere. (The radius of the Earth is 6 6.4 10 m, and atmospheric pressure at the surface is approximately 100 kpa.) Assume for the purposes of this question that the atmosphere is of uniform density. 2 (The surface area of a sphere is 4π R.) 14 a. 1.3 10 kg 16 b. 4.1 10 kg 18 c..2 10 kg 20 d. 3.4 10 kg 22 e. 6.3 10 kg 16. A large stone is resting on the bottom of the swimming pool. The magnitude of the normal force of the bottom of the pool on the stone is equal to the: a. weight of the stone. b. weight of the water displaced. c. sum of the weight of the stone and the weight of the displaced water. d. difference between the weight of the stone and the weight of the displaced water. e. cannot be determined without knowing the shape of the stone. 17. A window conducts power P from a house to the cold outdoors. What power is conducted through a window of half the area and half the thickness? a. 4P b. 2P c. P/4 d. P/2 e. P 18. A rectangular steel plate has a hole drilled through it. The plate is put into a furnace and heated. What happens to the inside diameter of the hole as its temperature increases? a. increases b. decreases c. remains constant d. becomes elliptical e. depends on the position of the hole on the plate. 19. A temperature change from 1 to 3 corresponds to what incremental change in K? a. 2.3 K b. 2.0 K c. 20 K d. 40 K e 300 K
20. A hot (70 ) lump of metal has a mass of 20 gm and a specific heat of 1046 J/kg. John drops the metal into a 00 gm calorimeter containing 7 g of water (specific heat 4186 J kg ) at 20. The calorimeter is constructed of a material that has a specific heat of 418 J/kg. Once the combination of metal, calorimeter and water reach equilibrium, what will be the final temperature? a. 114 b. 72 c. 64 d. 37 e. 20 21. If heat is flowing from a table to a block of ice sitting on top of the table, which of the following must be true? a. Static friction is acting to melt the ice. b. The ice is cooler than the table. c. The ice is changing phase. d. There must be a layer of liquid between the ice and the table. e. All four are possible, but none is absolutely necessary. 22. A 0.2 kg aluminum plate, initially at 20, slides down a 1 m long surface, inclined at a 30 angle to the horizontal. The force of kinetic friction exactly balances the component of gravity down the plane so that the plate, once started, glides down at a constant velocity. If all of the mechanical energy of the system is absorbed by the aluminum, what is its temperature increase of the plate at the bottom of the incline? (Specific heat for aluminum is 900 J / kg.) a. 0. b. 0.16 1m c. 0.08 d. 0.04 e. 0.03 30 o KEEP GOING!! THERE ARE TWO MORE QUESTIONS ON THE NEXT PAGE!
23. The surface of the sun has a temperature of about 800 K. If the radius of the sun is 8 7 10 m, determine the power output of the sun. 8 (Take ε = 1, and σ =.67 10 2 4 W/m / K. 2 The surface area of a sphere is 4π R ). a. 3.9 10 26 W b..17 10 27 W c. 9.62 10 28 W d. 6.96 10 30 W e. 7.21 10 32 W 24. The Stanford linear accelerator contains hundreds of brass disks tightly fitted into a steel tube (see figure). The coefficient of linear expansion of the brass is 2.00 10 - per. The system was assembled by cooling the disks in dry ice ( -7 ) to enable them to just slide into the close-fitting tube. If the diameter of a disk is 80.00 mm at 43, what is its diameter in the dry ice? a. 78.40 mm b. 79.8 mm c. 79.84 mm d. 80.00 mm e. 80.26 mm