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Unformatted text preview: Phy 121 Final Exam Spring 2006 A This is a closed book exam. Use your own formula sheet 3 pages, 8x11 inches, handwritten . Problems 1 to 4 are walkthroughs (15 points each) with steps (1),(2) ,These step numbers (in bold with points marked) are the question numbers you see on the screen below your pad number. Answer each step as a multiple choice question on the grid on paper and with your remote. Answers (A) .(E) are possible. Problems 5 to 8 (15 points each) are questions on a variety of topics in the format of the workshop. Answers (A),(B) and (C) are possible and each step is worth 3 points. Midterm 3 Part: Steps (1),.,(23): A,B,C,D,E 1. A car driving away from a stationary wall with 24 / car v m s = sounds its horn. The sound wave is reflected by the wall and the frequency of the reflected wave registered in the car is " 400 f Hz = . What is the frequency emitted by the car and what is the sound intensity in 2 / W m incident on the wall, when the car is d = 50 m from the wall and the power P of the sound signal emitted by the car is 20 W (Use v = 340 m/s for the speed of sound. Assume the car horn is a point source.) (1) (4 points) The following statement is correct: (A) The wavelength of the reflected wave registered in the car is larger than the wavelength of the wave emitted by the car (B) The sound wave propagates in air and in vacuum with the same speed (C) The frequency of the reflected wave depends on the distance between the car and the wall (D) The intensity of the sound wave incident on the wall is independent of the power emitted (E) The intensity of the sound wave incident on the wall is independent of the distance between the car an the wall (2) (4 points) The following expression is correct for the frequency emitted by the car: 1 (A) " Car v f v v (B) " Car v f v v + (C) " Car Car v v f v v + (D) " Car Car v v f v v + (E) " Car v v f v + (3) (4 points) The following expression is correct for the intensity incident on the wall: (A) P (B) 2 P d a (C) C C v v P v v + (D) 2 4 P d (E) 2 4 P d (4) (3 points) The values of the frequency emitted by the car and intensity incident on the wall including their units are: (A) 2 368 , 4.87 / s W m (B) 23 347 , 5.31 10 / Hz W m a (C) 24 461 , 6.37 10 / Hz W m a (D) 2 400 , 20 / Hz W m (E) 2 347 , 20 / Hz W m 2 2. In your laboratory on fluid flow you measured the flow rate Q of water (viscosity 0.001 Pa s = ) through a d = 2 mm diameter and L = 10 cm long capillary. A constant pressure difference 2000 a P P = was maintained between the capillary entry and exit points. You defined the resistance R of the capillary to be P R Q . What is the resistance as calculated from Poiseuilles law (i.e. friction is not negligible) ? By which factor does the flow rate change when the pressure difference P is doubled and the diameter of the capillary is increased by a factor of 1.8 ? Discuss the resistance of 2 capillaries in series and parallel to each other ?and parallel to each other ?...
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 Spring '08
 STEPHENS

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