PHYS 210 Final, Fall 2011

ail RL MTC... @ 10:07 PM @ 63% Timetaken 7 hour 49 mins Marks 86/107 Grade 80 out of a maximum of 100 (80%) 1 waks3 A Carnot engine has an efficiency of 43.5%. 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: [131.95 ] Correct Marks for this submission: 3/3. 2 war: 3 Suppose 4.00 mol of an ideal gas undergoes a reversible isothermal expansion from volume Vy to volume V2 = 6.3V, at temperature T = 400 K. Find the entropy change of the gas. Hint: Find the work done by the gas in the isothermal process first and then deduce aS Answer: (ez } Correct Marks for this submission: 3/3. wake An object moves in a circle at a constant speed. The work done on the object is zero because chose one © The displacement is zero in each cycle « The average force in each revolution is zero « There is no friction « The magnitude of the acceleration is constant « The force acting on the object is perpendicular to the velocity ¥ Incorrect Marks for this submission: 0/3. ail RL MTC... @ 10:07 PM @ 63% Incorrect Marks for this submission: 0/3. 4 weneea Lf a Material is very incompressible, which of the following is true about its bulk modulus? Chaase one answer, The bulk modulus is small. » © The bulk modulus is large. the bulk modulus is unrelated to the compressibility of the medium. « Correct Marks for this submission: 2/2. wets: Each part of the below Figure shows light that refracts through an interface between two materials. The incident ray (shown gray in the figure) consists of red and blue light. The approximate index of refraction for visible light is indicated for each material. Which of the three parts show physically possible refraction? Cha newer, _ (a) ‘ (b) « © fc) v (a) and (b) only « all of them (a), (b) and (c) « Correct Marks for this submission: 3/3. wets:3 The following four waves are sent along strings with the same linear densities (x is in meters and ¢ is in seconds). ail. RL MTC... @ 10:07 PM @ 63% Correct Marks for this submission: 3/3. 6 weks:3 The following four waves are sent along strings with the same linear densities (x is in meters and ft is in seconds). yl = 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. chess _ © yi has the highest wave speed, then y4, then y2 followed by ; the slowest wave speed for y3. v y3 has the highest wave speed, then y2, then y4 followed by the slowest wave speed for y1. « y3 has the highest wave speed, then y4, then y2 followed by the slowest wave speed for y1. « yl has the highest wave speed, then y2, then y4 followed by the slowest wave speed for y3 » Cannot tell need more information. » Correct Marks for this submission: 3/3. veks:3 A Q,2 kg mass moves along the x-axis; the potential energy (in Joules) of the system is Lif)= 8x? + 2x4 where x is in m. If the mass has a speed of 6.5 m/s at x= 1m, its speed at x = O is: Give your answer in m/s; do not put the unit. Answer: [a4 ] Incorrect Correct answer: 11.93 Marks for this submission: 0/3. ail RL MTC... @ 10:08 PM @ 63% weksss ~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, ~ 4cm « ~ 202m « OnSmse ew 25 mi « ww 2m 6 Correct Marks for this submission: 3/3. 9 wens:¢ 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 44°F? The linear expansion coefficient of steel is 11.10 ~© oc “1, Give your answer in cm. Do not put the unit next to your answer. Answer: ay ] Correct Marks for this submission: 4,/'4. 10 weks:3 Two slits separated by 0.10 mm are illuminated with green light (, = 540 nm). Calculate the distance (in cm) from the central bright-region to the ioth bright band if the screen is 1.0 m away. Give your answer in centimeters. Do not put the unit. Angwert “sa | Correct Marks for this submission: 3/3. ail RL MTC... @ 10:08 PM @ 63% Correct Marks for this submission: 3/3. 11 wens:2 Jf a longitudinal wave travels along a y-axis, in what direction do the particles oscillate? Chaase one answer, along x-axis « © along y-axis - along z-axis * Correct Marks for this submission: 2/2. i2 verkss3 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? cneoee one A has a larger average kinetic energy. « wer. B has a larger average kinetic energy. « © The gases have the same average kinetic energy. Correct Marks for this submission: 3/3. i3 wenss3 Consider two Stars A and B; Star A has 5 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. Angwert [400 ] Correct Marks for this submission: 3/3. 14 wees:3 AY mass starts from rest and moves along the x-axis ail RLMTC... @ 10:08 PM @ 63% 14 mexs:3 AA Mass starts from rest and moves along the x-axis under the influence of a net force that is proportional to t, its kinetic energy is proportional to Choose one te answer. On, tt + ijt « t2 x Incorrect Marks for this submission: 0/3. 15 Marks: 3 A block has a volume of 8 cm3. When weighed ona spring scale calibrated in grams, the scale reads 20 g. What does the scale indicate (in grams) if the block is weighed while immersed in a liquid of density 2.0 g/cm3. Give your answer in grams; do not put the unit next to your answer. Angwert 4 ] Correct Marks for this submission: 3/3. 16 vees:? Radio waves differ from visible light waves in that radio waves: Choose one travel slower « angwer, have a higher frequency « travel faster « © have a lower frequency - require a material medium « Correct Marks for this submission: 2/2. ail RLMTC... @ 10:08 PM @ 63% Correct 17 Marks: 4 1a Marks: 3 19 Marks: 3 Marks for this submission: 2/2. In the below figure, a string, tied to a sinusoidal oscillator at P and running over a support at Q, is stretched by a block of mass m. Separation L = 1.1 m, linear density vw = 1.6 g/m, and the oscillator frequency f = 190 Hz. The amplitude of the motion at P is small enough for that point to be considered a node. A node also exists at Q. Uscillaiar What mass ™m allows (in Kg) the oscillator to set up the 3 harmonic (i.e. n = 3) on the string? Take g = 9.8 m/s?; Give your answer in Kg; do not put the unit next to your answer. Answer: [3.1694 ] Correct Marks for this submission: 4/4. A net 50 N force acts on a 2-kg mass that starts from rest. At the instant the mass has moved 2.0 m, the rate at which work is being done on the mass is Chaose one 2.5 W « answer. - 25 Wi « 75 W « © 100 w « 500 W ¥ Incorrect Marks for this submission: 0/3. The rate of heat flow by conduction through a slab ail RL MTC... @ 10:08 PM @ 63% Incorrect Marks for this submission: 0/3. 19 Marks: 3 The rate of heat flow by conduction through a slab does NOT depend upon the: chaose one temperature difference between opposite faces of the slab « — thermal conductivity of the slab « slab thickness « cross-sectional area of the slab « © specific heat of the slab + Correct Marks for this submission: 3/3. 20 Marks: 3 The below Figure shows four situations in which a red liquid and a gray liquid are in a U-tube. In one situation the liquids cannot be in static equilibrium; Which situation is that: any ies) Ia 4 Chaase ene © situation (2) ¥ answer. — situation(3) « situation(1) « - situation(4) « Correct Marks for this submission: 3/3. 21 Marks: 3 The sound intensity 1.4 m from point source is 0.50 W/m2. The power (in Watt) output of the source is: Answer: 12515 | Correct Marks for this submission: 3/3. ses:¢ An oil film (n = 1.45) floating on water (n' = 1.33) is ail RL MTC... @ 10:08 PM @ 63% Answer: 12515 ] Correct Marks for this submission: 3/3. 22 weks:¢ Ar oil film (nm = 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 om“ Chaose one Orange r answer. Blue « Red « © Green + Violet « Correct Marks for this submission: 4/4. vees:3 A automobile moving at 36 m/s passes a police car moving at 45 m/s in the opposite direction. If the frequency of the siren is 106 Hz relative to the police car, what is the frequency (in Hz) heard by an observer in the automobile after the police car passes the automobile? The speed of sound in air is 343 m/s. Do not put the unit. Answer: aay ] Correct Marks for this submission: 3/3. 24 wees:2 The force on the walls of a vessel of a contained gas ail RLMTC... @ 10:08 PM @ 63% 24 vekss2 The force on the walls of a vessel of a contained gas is due to: Chaase one answer, repulsive force between gas molecules « slight loss in average speed of a gas molecule after collision with wall « change in momentum of a gas molecule due to collision with wall © elastic collisions between gas molecules « inelastic collisions between gas molecules « Incorrect Marks for this submission: 0/2. 25 vees:3 A hollow cylinder of radius r =0.44 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: g=9.8 m/s?; Give your answer in m/s; do not put the unit next to your answer. Answer: SESE ] Incorrect Correct answer: 2.94 Marks for this submission: 0/3. 26 waks:> Weak background noises from a room set up the eth 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.