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Unformatted text preview: Physics 2C, Waves ...Optics-- Winter 2007 Instructor: B. Grinstein Final Exam INSTRUCTIONS: Fill, tear and return the bottom strip of the front page with your scantron. Keep the top portion of the front page and the rest of the quiz. Use a pencil #2 to ll your scantron. Write your code number and bubble it in under "EXAM NUMBER". Bubble in the quiz form (see letter A-- D at bottom of page) in your scantron under "TEST FORM" Useful numbers: speed of light c = 3.0 10 8 , Boltzman constant k = 1.38 10- 23 J/K, Avogadro's number N A = 6.022 10 23 , R = N A k = 8.314 J/K mol, 1 u = 1.66 10- 27 kg, 1 atm = 101.3 kPa 1) The mass ux of a uid into one side of a container is 5.0 kg/s; the mass ux owing out the other side of the container is 3.0 kg/s. Assuming the container is completely lled with the uid and that there are no other ways for the uid to get in or out, one can conclude that A) the density of the uid inside the container must be increasing B) the magnitude of the entrance velocity is smaller than the magnitude of the exit velocity C) the magnitude of the entrance velocity is larger than the magnitude of the exit velocity D) the entrance point has a smaller cross- sectional area than the exit point E) the entrance point has a larger cross- sectional area than the exit point 2) Find the magnitude of the wave velocity of an ocean wave whose displacement is given by y = 3.7 cos(2.2 x- 4.5 t ) where x and y are in meters and t is in seconds. A) 2.8 m/s B) zero m/s C) 1.5 m/s D) 2.0 m/s E) 3.6 m/s 3) 43.5 cm 75.3 cm A brass rod is 43.5 cm long and an aluminum rod is 75.3 cm long when both rods are at an initial temperature of 0C. The rods are placed in line with a gap of 1.2 cm between them. The distance between the far ends of the rods is maintained at 120.0 cm throughout. The temperature is raised until the two rods are barely in contact. The coefcients of linear expansion of brass and aluminum are 2.0 x 10- 5 K- 1 and 2.4 x 10- 5 K- 1 , respectively. In the gure, the temperature at which contact of the rods barely occurs, in C, is closest to: A) 471 B) 448 C) 426 D) 493 E) 403 4) Consider a brick that is totally immersed in water. The long edge of the brick is vertical. The pressure on the brick is A) greatest on the sides of the brick. B) greatest on the bottom of the brick. C) greatest on the top of the brick. D) the same on all surfaces of the brick. E) greatest on the face with largest area.--------------------------------------------------------------------------------------- Name________________________________________ Code- Number_________________________ Quiz Form- A page- 1 5) A 4.9 x 10 14 Hz laser emits a pencil- like, i.e., cylindircal, beam 5.0 mm in diameter, with a beam energy density of 0.60 J/m 3 . The power emitted by the laser is closest to: ( Hint : how is the Poyting vector related to the energy density? What does the Poynting vector tell you about the power emitted?) A) 11 kW B) 7.1 kW...
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- Winter '09