PHYS 210 Problems Useful Selection for Final, Fall 2011

2010final 1 Marks: 3 Marks: 3 Marks: 3 Marks: 3 A truck 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 164 Hz relative to the police car, what is the frequency (in Hz) heard by an observer in the truck as the police car approaches the truck? The speed of sound in air is 343 m/s. Do not put the unit. ‘Answer: Incorrect Correct answer: 208.58 Marks for this submission: 0/3. When the temperature of a copper penny is increased by 100 °C, its diameter increases by 0.17%. The area of one of its faces increases by: Choose one answer. 0.51% x 0.27% x 0.13% x 0.17% x 0.34% y Correct Marks for this submission: 3/3. A roller-coaster car has a mass of 500 kg when fully loaded with passengers. The car passes over a hill of radius 15.0 m, as shown. The force of the track on the car at the top of the hill is 2149 N. What is the car speed (in m/s) at the top of the hill? g = 9.80 m/s. 15m Answer: 9.085 Correct Marks for this submission: 3/3. One mole of ideal gas is initially at Pp) = 1 atm and Vo= 25 Liters is slowly heated so that its state moves in a straight line on a PV-diagram to a final state P = 3 atm and V = 87 L. The work done (in Kilo Joules) by the gas is: 1 atm = 10° Pa. Give your answer in Kilo-Joules. Do not put unit. Answer: a Correct Marks for this submission: 3/3. 5 Marks: 3 The diagram shows a U-tube having cross-sectional area A and partially filled with oil of density 0. A solid cylinder, which fits the tube tightly but can slide without friction, is placed in the right arm. The system reaches equilibrium. The weight of the cylinder is: Choose one answer, Cannot tell, Need more information. AP (L4n)g x 2A (Lng x AP(Lch)g x ALPg y Incorrect Marks for this submission: 0/3. Marks: 3 Two slits are illuminated with green light () = 540 nm). The slits are 0.05 mm apart and the distance to the screen is 1.5 m. At what distance (in mm) from the central maximum on the screen is the average intensity 50% of the intensity of the central maximum? 1 nm = 10°? meter. Choose one answer. 0.4mm x 2mm x 1mm x 4mm 3mm x Incorrect Marks for this submission: 0/3. 7 A Carnot engine works between two reservoirs at temperatures of 300 K and 116 K. If the engine absorbs 100 J from the Marks: 3 hot reservoir, find the amount of work it does (in Joules): Answer: 613 Correct Marks for this submission: 3/3. Marks: 6 Marks: 3 10 Marks: 3 The Figure below shows how the stream of water emerging from a faucet “necks down” as it falls. The indicated cross- sectional areas are Ag = 1.20 cm? and A = 0.35 cm2. The two levels are separated by a vertical distance 55.5 mm. What is the volume flow (in cm3/ S) rate from the tap? i i h ih Hint: Use the Continuity Equation and the free fall equation. Give your answer in (cm3/s) and take g = 9.8 m/s2. Answer: Marks for this submission: 0/6. The equation of a wave, traveling along the +x axis with an amplitude of 0.02 m, a frequency of 440 Hz, and a speed of 330 m/s is given by: Choose one answer. Q y= 0.02 cos [88077 x/330 - 440t] x © y= 0.02 sin{@807r (x/330 - t)] ¥ ® — y= 0,02 sin (88077 (x/330 + t)] x QO ¥=0.02 cos [271 (W330 + 440t)] x OQ ¥=0.02 sin (277 (x/330 + 440t)] x A point source emits sound waves with a power output of 100 watts, What is the sound level (in dB) at a distance of 10 m? Choose one answer. Q v129dB x Q 11908 QO 10908 y Q 1398 x @ ~10db y core Marks for this submission: 0/3. 11 Marks: 3 An object moving along the x-axis is acted upon by a force Fy that varies with position as shown. How much work is done by this force as the object moves from x = 2m to x = 8m? F,(N) Choose one answer. ® +30) ¥ 10) x +50) x 30) x +10) x Correct Marks for this submission: 3/3. 12 Marks: 3 An organ pipe open at both ends has a radius of 4.0 cm and a length of 14 m. What is the frequency (in Hz) of the third harmonic? Assume the velocity of sound is 344 m/s. Do Not put unit next to your answer. Answer: 36.86 Correct Marks for this submission: 3/3. 13 Marks: 3 A light ray whose frequency is 6.00x10!4 Hz in vacuum is incident on piece of glass (n = 1.65). The wavelength of the light after it enters the glass is (in nm): Given: 1 nm = 10°9 meters; speed of light = 3.0 x108 m/s. Do not put unit Answer: 500 Incorrect Correct answer: 303.03 Marks for this submission: 0/3. 14 Marks: 3 Two strings are respectively 1.00 m and 2.00 m long. Which of the following wavelengths, in meters, could represent harmonics present on both strings? Choose one answer. © 1.33, 1.00, 0.500 x 2.00, 1.00, 0.500 y 2.00, 1.33, 1.00 x 4.00, 2.00, 1.00 x 0.800, 0.670, 0.500 x Incorrect Marks for this submission: 0/3. 15 Marks: 3 16 Marks: 3 7 Marks: 3 The frictional force of the floor on a large suitcase is least when the suitcase is: Choose one answer. ) pushed by a force parallel to the floor. ) tured on its side and pushed by a force parallel to the floor. ‘) pulled by a force directed at an angle f) above the floor. pushed by a force directed at an angle f) into the floor. dragged by a force parallel to the floor. Correct Marks for this submission: 3/3. The figure below represents a string which has a heavy section and a light section. The mass per unit length of the heavy section is 16 times as large as the mass per unit length of the light section. When the string is under tension, the wavelength of a wave traveling in the heavy section is times the wavelength of that same wave traveling in the light section. Choose one answer. ad fF} 12 x Way 2x 4x Correct Marks for this submission: 3/3. Unpolarized light is passed through three successive Polaroid filters, each with its transmission axis at 50° to the preceding filter. What percentage of light gets through? Your answer will be in percentile, i.e. a number between 0 and 100. ‘Answer: 8.54 Correct Marks for this submission: 3/3. 18 Marks: 3 A narrow slit is illuminated with sodium yellow light of wavelength ) = 589 nm. If the central maximum extends to + 30.0° , how wide is the slit? 1 2m = 10° meter. Choose one answer. 500 fim x 2.2 [Lm x 5.89 jm x 33.3 fm x 1.18 fim v Correct Marks for this submission: 3/3. 19 As the volume of an ideal gas is increased at constant pressure the average molecular speed: Marks: 2 Choose one answer. stays the same x increases at high temperature, decreases at low increases / ® decreases x decreases at high temperature, increases at low x Incorrect Marks for this submission: 0/2. 20 Marks: 3 At an instant when a 4.0-kg object has an acceleration equal to (5i + 3j) m/s2 , one of the two forces acting on the object is known to be (14i + 22j) N. Determine the magnitude of the other force (in Newtons) acting on the object. Do Not put unit. Answer: 1173 Correct Marks for this submission: 3/3. 2 vars:3 Four Wave functions are given below, I. y (x, t) = Ssin(4x - 20t + 4) IL y (x, t) = Ssin(3x - 12t + 5) IIL, y (x, t) = 5cos(4x + 24t + 6) IV. y (x, t) = 14cos(2x - 8t + 3) Rank the wave functions in order of the magnitude of the wave speeds, from least to greatest. Choose one answer, ) Well], My Il, 1,0, 1V x VN, 0,1, 1 x N,1, 0,1 y TI, WV, 11,1 y Correct Marks for this submission: 3/3. 2 Marks: 3 One piston in a hydraulic lift has an area that is twice the area of the other. When the pressure at the smaller piston is increased by AP the pressure at the larger piston: a) increases by AP/2 b) increases by 2,4P c) increases by AP d) increases by 4AP e) does not change. Choose one answer, ‘Answer c) is correct Answer a) is correct Answer e) is correct x Answer b) is correct ‘Answer D) is correct Incorrect Marks for this submission: 0/3. 23 Marks: 3 24 Marks: 3 & Marks: 3 A soap bubble (n = 1.35) is floating in air. If the thickness of the bubble wall is 106 nm, what visible light wavelength is most strongly reflected? = 475 510 570 680 Wavelength [nm] Choose one answer. A Orange x Violet Yellow ¥ Red x Blue x Correct Marks for this submission: 3/3. An ideal gas undergoes an isothermal process starting with a pressure of 200 kilo-Pa and a volume of 6 cm3, Which of the following might be the pressure and volume of the final state? Choose one answer. 300 kilo-Pa and6 cm3 x 100 kilo-Pa and 10 cm3_ x 600 kilo-Pa and 2cm3 y 800 kilo-Pa and 2cm3 400 kilo-Paand4cm3 x Correct Marks for this submission: 3/3. A circus performer stretches a tightrope between two towers. He strikes one end of the rope and sends a wave along it toward the other tower. He notes that it takes 0.8 s for the wave to travel the 20 m to the opposite tower, If one meter of the rope has @ mass of 0.38 kg, find the tension in the tightrope, Answer, 205 Correct Marks for this submission: 3/3, 26 Marks: 3 Asolid has a volume of 8 cm3, When weighed on a spring scale calibrated in grams, the scale indicates 20 g. What does the scale indicate if the object is weighed while immersed in a liquid of density 2 g/cm3? Choose one answer. 2) ~4grams y ~ 12 grams x ~ 16 grams x ~ 10 grams x zero, since the object will float x Correct Marks for this submission: 3/3. 27 A rock attached to a string swings in a vertical circle. Which free body diagram could correctly describe the force(s) on the rock when it is at the Marks: 3 highest point? N F w w w Ww Choose one answer. 2 Diagrams b) andc) x Diagrams a) and c) ¥ Diagrams a) and b) x Diagrams a) and d) x Diagram e) x Incorrect Marks for this submission: 0/3. 28 warks:3 A block of mass my = 3.70 Kg on a frictionless inclined plane of angle 9 =30 degrees is connected by a cord over a small frictionless, massless pulley to a second block of mass my = 3.65 Kg hanging vertically. What is the acceleration (in m/s?) of each block? Take g = 9.8 m/s? Do Not put unit. Answer: 9,08 Incorrect Correct answer: 2.40 Marks for this submission: 0/3. 9 In an adiabatic process: Marks: 2 Choose one answer. *) the work done by the environment on the system equals the change in internal energy / the energy absorbed as heat equals the change in internal energy the work done by the system on its environment equals to the change in internal energy x the energy absorbed as heat equals the work done by the system on its environment the energy absorbed as heat equals the work done by the environment on the system Correct Marks for this submission: 2/2. 30 Marks: 3 Suppose 4.00 mol of an ideal gas undergoes a reversible isothermal expansion from volume V; to volume V2 = 5.4V/ 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: 56.056 Correct Marks for this submission: 3/3.