EF 152 Exam 2 - Fall, 2017 Page 1 Version: A Copy 260 Name: Seat Assignment: Specify your EXAM ID on the right. Use 000 if you do not know your exam ID. Circle your TEAM SECTION 11:10 12:40 2:10 TA216 Cole TB216 Cole TC216 Cole TA217 Chris E TB217 Chris E TC217 Chris E TA218 Chris R 0 0 0 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 6 6 6 7 7 7 8 8 8 9 9 9 Instructions Do not open the exam until instructed to do so. Do not leave if there is less than 5 minutes to go in the exam. When time is called, immediately stop writing, remain seated, and pass your exam to the center aisle. Working after time is called results in an automatic deduction. Turn your equation sheets in with your exam. Guidelines Assume 3 significant figures for all given numbers unless otherwise stated Show all of your work no work, no credit Write your final answer in the box provided Include units for all answers
EF 152 Exam 2 - Fall, 2017 Page 2 Version: A Copy 260 1. (2 pt) An object is in simple harmonic motion with amplitude A. At what position does it have maximum kinetic energy? x = 0 x =0.25 A x = 0.50 A x = 0.75 A x = A 2. (2 pt) An object is in simple harmonic motion with amplitude A. What is its acceleration when x = A? positive 0 negative 3. (2 pt) A meter stick is hung from a point 0.1 m from its end and oscillates as a physical pendulum. What value should be used for r when calculating its mass moment of inertia (I = I cm + mr 2 )? 0.1 m 0.4 m 0.5 m 1 m 4. (2 pt) A tornado warning siren can produce a sound of intensity 0.4 W/m 2 at 15 m away. What is the intensity at 30 m away? 1.6 W/m 2 0.8 W/m 2 0.4 W/m 2 0.2 W/m 2 0.1 W/m 2 5. (2 pt) How would you calculate the wave speed of a standing wave? v = 0 v = λ*f ω*a ω*cos(kx-ωt) 6. (2 pt) A trumpeter plays at a sound level of 80 db. Three other trumpet players join in, each playing at the 80 db. What is the combined sound level of all four trumpeters? 80 db 86 db 120 db 160 db 320 db 7. (2 pt) A tuning fork produces a steady 400 Hz tone. When struck and held near a vibrating guitar string, 10 beats are counted in 5 seconds. What is a possible frequency of the guitar string? 400 Hz 400.5 Hz 402 Hz 405 Hz 410 Hz 450 Hz
EF 152 Exam 2 - Fall, 2017 Page 3 Version: A Copy 260 8. (2 pt) Which type of wave has a larger speed radio wave or microwave? radio wave microwave same speed 9. (2 pt) In the general wave equation y(x,t) = A cos(kx ωt), what does k represent? spring constant wave number stiffness mass / length 10. (2 pt) In the general harmonic motion equation x(t) = a 1 sin(ωt) + a 2 cos(ωt), what does a 2 represent? phase angle amplitude initial velocity initial displacement 11. (2 pt) When a light wave goes between air (n=1) and water (n=1.33), what remains the same? speed frequency wavelength 12. (5 pt) A light source is positioned in a pool of liquid where its ray starts to have total reflection at the surface where it meets the air. Determine the index of refraction of the liquid. n air=1.0 900 mm 400 mm 13. (5 pt) Two cars are headed toward each. Car A has a speed of 35 m/s and Car B has a speed of 10 m/s. Car A honks its horn with a frequency of 180 Hz. What frequency is heard in Car B?
EF 152 Exam 2 - Fall, 2017 Page 4 Version: A Copy 260 14. (5 pt) The 8 th harmonic of a pipe with both ends open is 2000Hz. What is the length of the pipe? 15. (5 pt) Dean Davis plucks a guitar string to produce a note with a fundamental frequency of 220 Hz. The string is 24 inches long and has a tension of 300 lb. What is the weight of the string? 16. (5 pt) A longitudinal wave travels 800 m down a cable in 0.07 seconds. What is Young s Modulus for the cable if its density is 2830 kg/m 3? 17. (5 pt) What is the length of a simple pendulum that has a period of exactly 3.2 seconds?
EF 152 Exam 2 - Fall, 2017 Page 5 Version: A Copy 260 18. (12 pt) A 42 kg professor demonstrating a physical pendulum takes 7.4 seconds to complete 4 swings when hanging from a point that is 61 cm above his center of mass. What is his mass moment of inertia about his center of mass? 19. (12 pt) The wave shown is moving at a velocity of +1.25 m/s. What is the y value for a particle on the wave at location x=1.7 m at time=0.6 seconds? 12 m 8 m
EF 152 Exam 2 - Fall, 2017 Page 6 Version: A Copy 260 20. (12 pt) 102,455 fans shout Go Vols at the same time, with each fan yelling with a level of 85 db at 1 meter. Assume Smokey is 50 meters away from each fan. What is the sound level that Smokey hears? 21. (12 pt) Dr Bennett spots some coins in a wishing pond. How far (d) is he from the coins? 55 d 2.2 m n = 1.1 1.8 m n = 1.5