Phys 220 Final Exam Dec Record 11 as your two-digit exam version on the scantron form

Transcription

1 Phys 220 Final Exam Dec Record 11 as your two-digit exam version on the scantron form Name : (Last) (First) (Middle) PUID: 1. Record 11 as your two-digit exam version on the scantron form in the field TEST/QUIZ NUMBER. 2. Write your name here and on the scantron form. 3. Record your PUID number here and in the STUDENT IDENTIFICATION NUM- BER field on your scantron form. 4. You are allowed a pencil and calculator (without internet access) only. 5. Answer all questions. Each question has equal weight, maximum total is 200 points.

2 Phys 220 Final Exam Dec. 11, What s the fastest way to make a U-turn at constant speed? Suppose that you need to make a 180 turn on a circular path. The minimum radius (due to the car s steering system) is 5.0 m, while the maximum (due to the width of the road) is 20.0 m. Your acceleration must never exceed 3.0 m/s 2 or else you will skid. Should you use the smallest possible radius, so the distance is small, or the largest, so you can go faster without skidding, or something in between? What is the minimum possible time for this U-turn? A. largest, 3.6 s B. smallest, 3.1 s C. smallest, 4.1 s D. largest, 5.2 s E. largest, 4.1 s 2. One balloon contains exactly 3 moles of helium atoms, and a second balloon contains exactly 3 moles of argon atoms. The mass of an argon atom is about 9 times greater that the mass of a helium atom. If the internal energies of these two systems are equal, what can we conclude? A. They must have the same temperature. B. They must have the same volume. C. They must have the same pressure. D. They must have the same pressure, volume, and temperature. E. None of the above.

3 Phys 220 Final Exam, Page 2 of 11 Dec. 11, Find the tangential acceleration of a freely swinging pendulum when it makes an angle θ with the vertical (the figure below ). A. g sin 2 (θ) B. g sin(θ) C. g tan(θ) D. g cos(θ) E. g cos 2 (θ) 4. A spring used in an introductory physics laboratory stores 10.0 J of elastic potential energy when it is compressed 0.20 m. Suppose the spring is cut in half. When one of the halves is compressed by 0.20 m, how much potential energy is stored in it?. A. 5.0 J B J C J D J E J

4 Phys 220 Final Exam, Page 3 of 11 Dec. 11, The three bodies in the figure below each have the same mass. If one of the bodies is moved 12 cm in the positive x-direction, by how much does the center of mass move? A. 4.0 cm in the negative x-direction B. 6.0 cm in the positive x-direction C. 4.0 cm in the positive x-direction D. 2.0 cm in the negative x-direction E. 2.0 cm in the positive x-direction 6. A submarine of mass kg and initially at rest fires a torpedo of mass 250 kg. The torpedo has an initial speed of m/s. What is the initial recoil speed of the submarine? Neglect the drag force of the water. A m/s B m/s C m/s D m/s E m/s

5 Phys 220 Final Exam, Page 4 of 11 Dec. 11, Water entering a house flows with a speed of 0.20 m/s through a pipe of 2.0 cm inside diameter. What is the speed of the water at a point where the pipe tapers to a diameter of 5.0 mm? A. 2.2 m/s B. 4.2 m/s C. 6.2 m/s D. 8.2 m/s E. 3.2 m/s 8. You want to build a raft that can hold you (83 kg) plus some supplies (39 kg) for a long trip. You decide to make the raft out of logs that are each 19 cm in diameter and 2.9 m long. If the density of each log is 595 kg/m 3, how many logs do you need? A. 1 B. 4 C. 2 D. 5 E. 3

6 Phys 220 Final Exam, Page 5 of 11 Dec. 11, The longest string (a thick metal wire) on a particular piano is 2 m long and has a tension of 300 N. It vibrates with a fundamental frequency of 27.5 Hz. What is the total mass of the wire? A kg B kg C kg D kg E kg 10. Doppler ultrasound is used to measure the speed of blood flow. If the speed of the red blood cells is v, the velocity of sound in blood is c, the ultrasound source emits waves of frequency f, and we assume that the blood cells are moving directly toward the ultrasound source, then the frequency f r of reflected waves detected by the apparatus is given by f r = f(1 + v/c)/(1 v/c). Suppose the reflected sound interferes with the emitted sound, producing beats. If the speed of red blood cells is 0.10 m/s, the ultrasound frequency used is 5.0 MHz, and the velocity of sound in blood is 1570 m/s, what is the beat frequency? A. 5.1 MHz B. 640 Hz C. 610 Hz D. 5.2 MHz E. 650 Hz

7 Phys 220 Final Exam, Page 6 of 11 Dec. 11, What fraction of the air molecules in a house must be pushed outside while the furnace raises the inside temperature from 13 Celsius to 23 Celsius? The pressure does not change since the house is not 100% airtight. A B C D E A smoke particle has a mass of kg and it is randomly moving about in thermal equilibrium with room temperature air at 27 C. What is the rms speed of the particle? A. 3.5 cm/s B. 3.5 m/s C. 2.8 cm/s D. 3.0 m/s E. 3.0 cm/s

8 Phys 220 Final Exam, Page 7 of 11 Dec. 11, If 30.0 kcal of heat are supplied to g of water at 22 C, what is the final temperature of the water? A. 355 K B. 300 K C. 325 K D. 375 K E. 395 K 14. A monatomic gas at 27 C undergoes a constant volume process from A to B and a constant pressure process from B to C, as shown in the figure below: Find the total work done during these two processes. A J B J C J D J E J

9 Phys 220 Final Exam, Page 8 of 11 Dec. 11, A bucket filled with dirt of mass 20 kg is suspended by a rope that hangs over a pulley of mass 29 kg and radius 0.15 m (figure below). Everything is initially at rest, but someone is careless and lets go of the pulley and the bucket then begins to move downward. What is the speed of the bucket when it has fallen a distance of 2.0 m? The moment of inertia for a disk of mass m and radius r is 1 2 mr2. A. 8.4 m/s B. 5.2 m/s C. 2.4 m/s D. 4.8 m/s E. 3.3 m/s

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