PHYS 210 Final Moodle, Fall 2011

Marks: 3 A Carnot engine has an efficiency of 24.0%. It operates between constant-temperature reservoirs differing in temperature by 57.4 °C. In kelvins, what is the temperature of the hot reservoir. Give your answer in Kelvin; do not put the unit next to your answer. Answer: 1376.6 Incorrect Correct answer: 239.17 Marks for this submission: 0/3. Marks: 2 Air enters a hot-air furnace at 7°C and leaves at 77°C. If the pressure does not change each entering cubic meter of air expands to: Choose one answer. ~ 0.8 m? x @ ~1.25m9 vy ~ 1.9m? x ~7.0m? x ~1im? x Correct Marks for this submission: 2/2. 20 Marks: 3 The following four waves are sent along strings with the same linear densities (x is in meters and t is in seconds). yi = 3sin(x-3t) y2 = 6sin(2x-t) y3 = sin(4x-t) y4 = 2sin(x-2t) Rank the waves according to their wave speed, greatest first. Choose one answer. ® y1 has the highest wave speed, then y4, then y2 followed by the slowest wave speed for y3. ¥ y3 has the highest wave speed, then y2, then y4 followed by the slowest wave speed for y1. x y3 has the highest wave speed, then y4, then y2 followed by the slowest wave speed for y1. x y1 has the highest wave speed, then y2, then y4 followed by the slowest wave speed for y3_ x Cannot tell need more information. x Correct Marks for this submission: 3/3. 21 Marks: 2 Radio waves differ from visible light waves in that radio waves: Choose one answer. travel slower x have a higher frequency x travel faster x © have a lower frequency ¥ require a material medium x Correct Marks for this submission: 2/2. 22 If a material is very incompressible, which of the following is true about its bulk modulus? Marks: 2 Choose one answer. The bulk modulus is small. x @ The bulk modulus is large. ¥ the bulk modulus is unrelated to the compressibility of the medium. x Correct Marks for this submission: 2/2. 23: The below Figure shows four situations in which a red liquid and a gray liquid are in a U-tube. In one situation the Meni 2 liquids cannot be in static equilibrium; Which situation is that: a @ ® “ Choose one answer. O} situation (2) ¥ situation(3) x situation(1) x situation(4) x Correct Marks for this submission: 3/3. 24 . : Marks: 3 An object moves in a circle at a constant speed. The work done on the object is zero because Choose one answer. The displacement is zero in each cycle x The average force in each revolution is zero x There is no friction x The magnitude of the acceleration is constant » @ The force acting on the object is perpendicular to the velocity y Correct Marks for this submission: 3/3. 25 Marks: 3 Weak background noises from a room set up the 9th harmonic standing wave in a cardboard tube of length 0.67 m with two open ends. Assume that the speed of sound in the air within the tube is 343 m/s. What frequency (in Hz) do you hear from the tube? Answer: 2303.73 Correct Marks for this submission: 3/3. 26 Marks: 2 The force on the walls of a vessel of a contained gas is due to: Choose one answer. repulsive force between gas molecules x slight loss in average speed of a gas molecule after collision with wall x @ change in momentum of a gas molecule due to collision with wall y elastic collisions between gas molecules x inelastic collisions between gas molecules x Correct Marks for this submission: 2/2. 27 . . . . Marks: 3 Consider two Stars A and B; Star A has 6.2 times the radius and twice the absolute temperature of star B? What is the ratio of star A’s power output to star B’s output due to electromagnetic radiation? The emissivity of both stars can be assumed to be the same. Give your answer with two digit after the decimal point: Ex: 0.46 or 4.27. Answer: 615.04 Correct PE EE Se ER 28 Marks: 3 If you start with two sinusoidal waves of the same amplitude traveling in phase on a string and then somehow phaseshift one of them by 5.4 wavelengths, what type of interference will occur on the string? Choose one answer. @ _ Intermediate (closer to fully destructive) ¥ Intermediate (closer to fully constructive) x Fully destructive x Fully constructive x Cannot tell, need to know the phase difference. x Correct Marks for this submission: 3/3. 29 Marks: 3 Gas A has molecules with small mass. Gas B has molecules with larger mass. They are at the same temperature. How do the gases compare with respect to the average translational kinetic energy? Choose one answer. Ahas a larger average kinetic energy. x B has a larger average kinetic energy. x @ The gases have the same average kinetic energy. ¥ Correct Marks for this submission: 3/3. 30 Marks: 4 An oil film (n = 1.45) floating on water (n' = 1.33) is illuminated by white light at normal incidence. The film is 280 nm thick. Find the color of the light in the visible spectrum most strongly reflected: 475 510 570 650 Wavelength [nm] Choose one answer. Orange x @ Blue x Red x Green y Violet x Incorrect Marks for this submission: 0/4. 31 Marks: 3 In a hot summer day the average temperature in Beirut is 35 °C, on that same day the temperature in Barouk mountain is 5 °C, the rms speed of the gas molecules in Barouk is decreased by: Choose one answer. @ 5.2% ¥ 14.2% x 46% x 21% x 31% x Correct Marks for this submission: 3/3. 32 Marks: 4 A building made with a steel structure is 650 m high on a winter day when the temperature is 0°F. How much taller (in cm ) is the building when it is 74°F? The linear expansion coefficient of steel is 11x 10 Sec -!, Give your answer in cm. Do not put the unit next to your answer. Answer: 29.4 Correct Marks for this submission: 4/4. 33 Marks: 3 The sound level at a point P is 14 db below the sound level at a point 1.0 m from a point source. The distance from the source to point P is: Choose one answer. ~4om x ~ 202m x ~Smy ~25m x ~2m x Correct Marks for this submission: 3/3. 34 - Marks: 3 An ideal monatomic gas at initial temperature To (in kelvins) expands from initial volume Vo to volume 2Vo by each of the five processes indicated in the T-V diagram shown below. Ty & 0.637, Volume Which preocesses correspond to isothermal and isobaric, respectively. Choose one answer. AE and Ac y @ AEandAB yx AD andAF y» 35 Marks: 3 36 Marks: 3 A hollow cylinder of radius r =0.46 m is spun about a horizontal axis. A stone located inside the cylinder gets stuck to the wall. When the stone is at the highest point, it exerts a force equal to its weight on the wall of the cylinder, tangential speed (in m/s) of the stone is: oa ae g=9.8 m/s2; Give your answer in m/s; do not put the unit next to your answer. Answer: 424 Marks for this submission: 0/3. A hydraulic press has one piston of diameter 5 cm and the other piston of diameter 18.0 cm. If a 10,000 N car is resting on the large piston, the force exerted on the smaller to lift the car is Answer: 429600 Marks for this submission: 0/3.