General Physics II PHYS 102 Final Exam Spring st May 2011

Transcription

1 Qatar University Arts and Sciences College Mathematics and Physics Department General Physics II PHYS 102 Final Exam Spring st May 2011 Student Name: ID Number: 60 Please read the following carefully before start answering Make sure that you have 6 pages including three questions, I, II, and III. Question I consists of 25 multiple choice questions. For each question in I there is 5 alternative answers lettered a, b, c, d, and e. You should choose the answer and indicate your choice in pen by a tick ( ). Make sure that only ONE of the alternatives is ticked for each question. Two answers to one question will result in loss of the mark of that question. Answer all questions in pen and in a clean, clear and tidy way. All work must be done on your paper; no loose papers are allowed to be in the exam. Show all the steps of your work. Calculators are permitted but no electronic dictionaries or mobile phones. Time allowed for this exam is 120 minutes. Do not spend long time on a particular question. A list of physical constants is provided in the last page. At the end of the exam, please hand in your paper and make sure that your name is written. I. Choose the best answer for each question. 1. Write the equation of a wave, traveling along the +x axis with an amplitude of 0.02 m, a frequency of 440 Hz, and a speed of 330 m/sec. a. y = 0.02 sin [880 (x/330 t)] b. y = 0.02 cos [880 x/ t] c. y = 0.02 sin [880 (x/330 + t)] d. y = 0.02 sin [2 (x/ t)] e. y = 0.02 cos [2 (x/ t)] 50 2.Two traveling waves have the forms z 1 = A sin(kx - ωt), z 2 = A sin(kx + ωt). Express their superposition in the form of a standing wave. a. 2A cos(kx) cos( ωt ) b. 2A sin(kx) cos( ωt ) c. 2A sin(kx) sin( ωt ) d. A sin[(kx ) 2 - (ωt ) 2 ] e. 2A cos(kx) sin( ωt ) 1/6

2 3.A mass is attached to a vertical spring and bobs up and down between points A and B. Where is the mass located when its kinetic energy is a minimum? a. at either A or B b. midway between A and B c. one-third of the way between A and B d. one-fourth of the way between A and B e. none of the above 4.The maximum speed of a 3.00-kg object in simple harmonic motion is 4.00 m/s. The maximum acceleration of the object is 5.00 m/s 2. What is the period of the simple harmonic motion? a s b s c s d s e s 5.The position of a mass that is oscillating on a spring is given by x = (12.3 cm) cos[(1.26s -1 )t]. What is the velocity of the mass when t = s? a cm/s b cm/s c cm/s d cm/s e. 0 cm/s 6.A laser beam strikes a reflecting surface with an angle of incidence of 43. What is the angle between the incident ray and the reflected ray? a. 43 o b. 86 o c. 45 o d. 90 o e. 0 o 7.A light ray in water passes into air. The angle of incidence in the water is 40. What is the angle of refraction in air if the index of refraction of water is 1.33? a. 59 o b o c. 40 o d o e. 29 o 8.An optic fiber is made of clear plastic with index of refraction of For what angle of incidence will light remain within the plastic "guide"? a. > 21.1 o b. > 23.4 o c. > 38.3 o d. > 40.3 o e. > 41.8 o 2/6

3 9.White light is spread out into spectral lines by a grating. If the grating has 2000 lines per centimeter, at what angle will red light (640 nm) appear in the first order? a o b o c o d o e o 10. The colors on a soap bubble are caused by reflection and a. Diffraction b. interference c. refraction d. dispersion 11. In a two-slit experiment, the slit separation is m. The interference pattern is created on a screen that is 2.00 m away from the slits. If the seventh bright fringe on the screen is a linear distance of 10.0 cm away from the central fringe, what is the wavelength of the light? a. 100 nm b. 204 nm c. 214 nm d. 224 nm e. 234 nm 12. An image is 4.0 mm in front of a converging lens with focal length 5.0 mm. Where is the object? a. 2.2 mm in front of the lens b. 2.2 mm behind the lens c. 9.0 mm in front of the lens d. 9.0 cm behind the lens e. 20 mm in front of the lens 13. The side mirror on a car is convex and has a radius of curvature of 25 cm. Another car is following, 20 m behind. If the height of the car is 1.6 m, how tall is the image? a. 5 cm b. 2 cm c. 4 cm d. 3 cm e. 1 cm 14. A sound source emits 30.0 W of sound power spread equally in all directions. What is the sound intensity level 30.0 m from the source? a db b db c x 10-3 db d x 10-3 W e db 3/6

4 15. Consider an open pipe of length L. What are the wavelengths of the three lowest tones produced by this pipe? a. 4L, 2L, L b. 2L, L, L/2 c. 2L, L, 2L/3 d. 3L, L, L/3 e. 2L, L, L/2 16. The sound from a single source can reach point O by two different paths. One path has a length of 20.0 m and the second path has a length of 21.0 m. The sound destructively interferes at point O. What is the minimum frequency of the source if the speed of sound is 340 m/s? a. 340 Hz b Hz c. 520 Hz d. 680 Hz e. 170 Hz 17. A sample of helium (He) occupies 44.8 L at STP. What is the mass of the sample? a. 2 g b. 4 g c. 6 g d. 8 g e. 10 g 18. What is the average kinetic energy of a nitrogen molecule in the air in a room in which the air temperature is 17.0 C? a x J b x J c x J d x J e x J 19. The coefficient of volume expansion of olive oil is K-1. A 1-liter glass beaker is filled to the brim with olive oil at room temperature. The beaker is placed on a range and the temperature of the oil and beaker increases by 25 o C. As a result, liters of olive oil spill over the top of the beaker. What is the coefficient of linear expansion of glass? a. 1 x 10-6 K -1 b. 4 x 10-6 K -1 c. 1 x 10-5 K -1 d. 2 x 10-5 K -1 e. 3 x 10-5 K -1 4/6

5 20. Two metal rods are to be used to conduct heat from a region at 100 C to a region at 0 C as shown in the figure. The rods can be placed in parallel, as shown on the left, or in series, as on the right. The heat conducted in the series arrangement is a. greater than the heat conducted with the rods in parallel b. the same as the heat conducted with the rods in parallel c. less than the heat conducted with the rods in parallel d. impossible to compare with the heat conducted with the rods in parallel 21. The filament in a light bulb has a diameter of mm and an emissivity e = 1.0. The temperature of the filament is 3000 C. How long should the filament be in order to radiate 60 W of power? a. 11 cm b. 9.4 cm c. 8.6 cm d. 7.2 cm e. 5.9 cm 22. An athlete doing exercises performs 650 kj of work and loses 425 kj of heat. What is the change in the internal energy of the athlete? a kj b kj c kj d. 225 kj e. 276 kj kcal of heat raises the temperature of 2.0 kg of material by 400 o F. What is the material's specific heat capacity? a kcal/kg C b kcal/kg C c kcal/kg C d kcal/kg C e kcal/kg C 24. How much heat needs to be removed from 100 g of 85 C water to make -5 C ice? The specific heat of water and ice are 4186 and 2100 J/(kg.K), respectively. The latent heat of fusion and vaporization of water are 333 and 2260 kj/kg, respectively. a. 255 cal b. 168 kcal c. 8.5 kcal d kcal e kcal 25. A certain engine extracts 1300 J of heat from a hot temperature reservoir and discharges 700 J of heat to a cold temperature reservoir. What is the efficiency of this engine? a. 46% b. 54% c. 86% d. 27% e. 13% 5/6

6 26. During an isothermal process, 5.0 J of heat is removed from an ideal gas. What is the change in internal energy? a. 0 b. 2.5 J c. 5.0 J d. 7.5 J e. 10 J II. 1. What is Doppler Effect? Explain briefly one application of Doppler effect A factory siren indicating the end of a shift has a frequency of 90.0 Hz. What frequency is received by the occupant of a car traveling towards the factory at 25 m/s? 3. How fast is the Concorde moving if it reaches Mach number of 1.5? III. 1. Distinguish between mechanical and electromagnetic waves and give one example of each type The three waves A, B and C shown in the figure propagate on strings with equal tensions and equal mass per length. Rank the waves in order of increasing (a) frequency, (b) wavelength, and (c) speed. With my best wishes Dr. Dana Abdulmalik 6/6