PHYS 210 Final With Solutions, Fall 2013

‘Mark 0.00 out of 3.00 © Flag question ‘Mark 3.00 out of 3.00 Flag question ‘Mark 4.00 out of 4.00 & Flag question ‘Mark 3.00 out of 3.00 © Flag question ‘Mark 0.00 out of 4.00 Flag question A particle starts from rest at x=o and moves along the x-axis with a kinetic energy that increases linearly with time; the x-position of the particle Select one: is proportional to time is proportional to t*!? is proportional to t/? © is proportional to t? is proportional to t3/? ‘The correct answer is: is proportional to t’? Two identical objects interact with each other but with no other objects. Initially object A has a speed of 5 m/s and object B has a speed of 10 m/s. The objects move around and finally return to their initial positions; now A has a speed of 4 m/s and B has a speed of 7 m/s. One can conclude that Select one: The potential energy decreased The potential energy increased The mechanical energy increased © The mechanical energy decreased The mechanical energy did not change The correct answer is: The mechanical energy decreased A heat engine operates between reservoirs at 200K and 100K. In each cycle it absorbs 100 J from the hot reservoir and loses 25J to the cold reservoir. This engine Select one: Violates only the first law of thermodynamics © Violates only the second law of thermodynamics Violates Both the first and second laws Does not violate either laws Violation of the laws of thermodynamics depends whether the gas is ideal or not The correct answer is: Violates only the second law of thermodynamics Alight ray whose frequency is 6.00 * 10“4 Hz in vacuum is incident on piece of glass (n = 1.55). The wavelength of the light after it enters the glass is Gn nm): Given: 1 nm = 10° meters; speed of light = 3.0 * 10° m/s. Do not put unit Answer: 322.58 The correct answer is: 322.58064516129 A4-kg block starts up a 30° incline with a speed of 5 m/s and comes to rest 2 m up the incline. The magnitude of the total work done on the block is: Select one: ~goJ ~sod ~307 ~107 © Cannot tell, need more information The correct answer is: ~ 50 J Question 6 Complete ‘Mark 2.00 out of 2.00 © Flag question ‘Mark 3.00 out of 3.00 P Flag question ‘Mark 0.00 out of 5.00 Flag question Mark 3.00 out of 3.00 YP Flag question Question 10 ‘Mark 3.00 out of 3.00 P Flag question Question 11 ‘Mark 0.00 out of 4.00 © Flag question ‘Mark 0.00 out of 3.00 P Flag question The diagram shows the passage of a ray of light from air into a substance X. The index of refraction of X is: Select one: 0.53 0.88 © 1.9 oie: 3.0 The correct answer is: 1.9 Three traveling sinusoidal waves are on identical strings, with the same tension. The mathematical forms of the waves are y (x,t) = y_sin(3x — 6), y, (0 = y, sin(4x — 84), and y(t) = y,,Sin(6x — 12), where xis in meters and fis in seconds. Match each mathematical form to the appropriate graph below. y | i i ii Select one: yi correspond to iii, y2 correspond to i, y3 correspond to ii yi correspond to i, y2 correspond to iii, y3 correspond to ii y1 correspond to iii, y2 correspond to ii, y3 correspond toi y1 correspond to ii, y2 correspond to i, y3 correspond to iii The correct answer is: y1 correspond to i, y2 correspond to ii, y3 correspond to iii Water is flowing with a speed of 3.0 m/s through a hole of diameter 1.0 cm located at the bottom of a barrel; the diameter of the stream of water, 20 em below the hole of the above bucket is: Hint: water falls under the influence of gravity; take g =9.8 m/s*. Select one: icm 12cm @srcm o.gicm 0.83 cm The correct answer is: 0.91 cm Arefrigerator has a coefficient of performance of 4. If the refrigerator absorbs 30 cal of heat from the cold reservoir in each cycle, the heat expelled in cal) into the hot reservoir is: 1cal = 4.1863 give your answer in calories. Select one: ~ 32.5 cal ®@ ~37.5¢al ~ 22.5 cal ~7.5 cal ~ 0.0 cal The correct answer is: ~ 37.5 cal A Carnot engine works between two reservoirs at temperatures of 300 K and 135 K. If the engine absorbs 100 J from the hot reservoir, find the amount of work it does (in Joules): Do not put unit next to your answer. Answer: 55 The correct answer is: 55 A garden hose with an internal diameter of 1.7 cm is connected to a (stationary) lawn sprinkler that consists merely of an enclosure with 25 holes, each 0.17 cm in diameter. If the water in the hose has a speed of 0.96 m/s, at what speed (in m/s) does it leave the sprinkler holes? Answer: 2.4 The correct answer is: 3.84 An aluminum flagpole is 51.5 m high. By how much does its length increase (in centimeters) as the temperature increases by 23 C°? (The linear expansion coefficient of aluminum is 23 * 10° /C?,) Give your answer in cm. do not put the unit. Answer: 0.0002724 The correct answer is: 2.72435 Question 13 An object moves in a circle at constant speed. The work done by the centripetal force is zero because ‘Mark 0.00 out of ae Select one: rote © The displacement for each revolution is zero The average force for each revolution is zero There is no friction The average centripetal acceleration is zero The average tangential acceleration is zero The correct answer is: The average tangential acceleration is zero Question 14 Asource emits sound with a frequency of 1000Hz. It is moving at 21.3 m/s toward a reflecting wall. If the speed of sound is 340 m/s, an observer at ‘Complete rest directly behind the source hears a beat frequency (in Hz) of: Marko.cooatef 19 Not put the unit next to your answer; 5.00 © Flag question Answer: 66.834 The correct answer is: 125.78779120234 ‘Question 15 Asystem absorbs 278 J of heat reversibly from a reservoir at 350 K and gives off 110 J of heat reversibly to a reservoir at 220 K, what is the change of ‘Complete entropy of the system? Marko.cooutef = Give your answer in J/K. Do not put the unit. 3.00 Remove flag Answer: 1.29 The correct answer is: 0.29428571428571 Question 16 For one complete cycle of a reversible heat engine, which of the following quantities is NOT zero? Complete ‘Mark 3.00 out of Select one: eae the change in the entropy of the working gas YP Flag question the change in the pressure of the working gas the change in the internal energy of the working gas (O) the work done by the working gas the change in the temperature of the working gas The correct answer is: the work done by the working gas ‘Question 17 Unpolarized light is passed through three successive Polaroid filters, each with its transmission axis at 32° to the preceding filter. What percentage Complete of light gets through? tase cutaf Your answer will be in percentile, i.e. a number between o and 100. Tae Answer: 26 The correct answer is: 25.861424942804 Question 18 Ablock of mass M moves at a speed V on a horizontal frictionless surface. It hits and compresses a spring with a force constant k, which is attached to Complete a wall. At the instant when the kinetic energy of the block is equal to the potential energy of the spring, the spring is compressed by: ‘Mark 4.00 out of ates Select one: Y Remove flag © V(M/2k)*/? atv/4ko*/* (v/iy/? MV*/4k ¥a (MV/k)*/? The correct answer is: V(M/: ‘oky'/? Question 19 The rate of heat flow by conduction through a slab does NOT depend upon the: Complete Marko.oooutef ‘Select one: ane © temperature difference between opposite faces of the slab e . elena thermal conductivity of the slab slab thickness cross-sectional area of the slab specific heat of the slab The correct answer is: specific heat of the slab Question 20 Ifa standing wave on a string is given by a y (xt) = gsin(kx)cos(«. t) ‘Mark 2.00 out of a is there a node or an antinode of the oscillations of the string at x = 3 ) /4? © Flag question Select one: Node © Antinode The correct answer is: Antinode Answer: 0.0002724 The correct answer is: 2.72435 Question 21 Mark 3.00 out of 3.00 Flag question Question 22 ‘Mark 0.00 out of 4.00 Remove flag Question 23 ‘Mark 0.00 out of 3.00 P Flag question Question 24 ‘Mark 0.00 out of 3.00 © Flag question Question 25 Mark 4.00 out of 4.00 Remove flag The Figure below shows a standing wave oscillation at 100 Hz on a string of length 0.40 m and fixed on both ends. What is the speed of this wave? Select one: 40 m/s © 20m/s 30 m/s 80 m/s 10 m/s The correct answer is: 20 m/s A bubble having a diameter of 1.00 cm is released from the bottom of a swimming pool where the depth is 5.00 m. What will the diameter of the bubble be when it reaches the surface? The temperature of the water at the surface is 20.0 °C, whereas it is 15.0 °C at the bottom. (The density of water is 1.00 X 103 kg/m3,g = 9.8 m/s”, 1 atm = 1.01 105 Pa). Select one: 0.95 cm 1.15 cm 1.51¢m © 1.65cm 1.85 cm The correct answer is: 1.15 cm A particle is released from rest at a point x=A and moves along the x-axis subject to the potential energy function U shown. The particle will Select one: © Oscillate between A and D Oscillate between A and B Oscillate between C and D Oscillate between either A and B, or C and D The motion is unbound The correct answer is: Oscillate between A and B A Carnot cycle, operating as a heat engine, consists , in the order given, of Select one: an isothermal expansion, an isothermal compression, an adiabatic expansion and an adiabatic compression. an adiabatic expansion, an adiabatic compression, an isothermal expansion and an isothermal compression. © anisothermal expansion, an adiabatic compression, an isothermal compression and an adiabatic expansion. an adiabatic compression, an isothermal compression, an isothermal expansion and an adiabatic expansion. an isothermal expansion, an adiabatic expansion, an isothermal compression and an adiabatic compression. The correct answer is: an isothermal expansion, an adiabatic expansion, an isothermal compression and an adiabatic compression. Two blocks are released from the top of a building. One falls straight down while the other slides down a smooth ramp. If all friction is ignored, which one is moving faster when it reaches the bottom? Select one: The block that went straight down. The block that went down the ramp. © They both will have the same speed. Insufficient information to work the problem. The correct answer is: They both will have the same speed. wwe 8; Antinode Amsw ¢ 2002724 The cor: ct answer is: 2.72435 Question 26 ‘Mark 0.00 out of 3.00 Y Remove flag Question 27 ‘Mark 3.00 out of 3.00 Flag question Question 28 ‘Mark 0.00 out of 3.00 © Flag question Question 29 ‘Mark 0.00 out of 3.00 Remove flag Question 30 ‘Mark 0.00 out of 4.00 Remove flag Question 31 ‘Mark 0.00 out of 4.00 P Flag question Question 32 ‘Mark 0.00 out of 3.00 P Flag question During the time that latent heat is involved in a change of state: Select one: The temperature does not change. © The substance always expands. Achemical reaction takes place. Molecular activity remains constant. Kinetic energy changes into potential energy. The correct answer is: The temperature does not change. Suppose 4.00 mol of an ideal gas undergoes a reversible isothermal expansion from volume V, to volume V_ = 6.3V, at temperature T= 4oo K. Find the entropy change of the gas. Hint:Find the work done by the gas in the isothermal process first and then deduce :\S Answer: 61.18 The correct answer is: 61.209318608267 Molecules of gas in a container move a lot and fast; but the container never shakes because that would Select one: violate the first law produce the perfect engine produce the perfect refrigerator require hotter gas © require better thermal contact with the environment The correct answer is: produce the perfect engine The difference in entropy AS = S, — S,, for two states A and B of a system can computed as the integral {dQ/T provided: Select one: © Aand Bare on the same adiabat Aand B have the same temperature a reversible path is used for the integral the change in internal energy is first computed the energy absorbed as heat by the system is first computed The correct answer is: a reversible path is used for the integral The mathematical forms for the three sinusoidal traveling waves are given by wave 1: y(x,t) = (2 em) sin (3x — 6t) wave 2: y(x,t) = (3 cm) sin (4x — 121) wave 3: y(x,t) = (4 cm) sin (5x — 111) where x is in meters and t is in seconds. Of these waves: Select one: wave 1 has the greatest wave speed and the greatest maximum transverse string speed (0) wave 2 has the greatest wave speed and wave 1 has the greatest maxmium transverse string speed wave 3 has the greatest wave speed and the greatest maximum transverse string speed wave 2 has the greatest wave speed and wave 3 has the greatest maximum transverse string speed wave 3 has the greatest wave speed and wave 2 has the greatest maximum transverse string speed The correct answer is: wave 2 has the greatest wave speed and wave 3 has the greatest maximum transverse string speed an adiabatic compression, an isothermal compression, an isothermal expansion and an adiabatic expansion. an isothermal expansion, an adiabatic expansion, an isothermal compression and an adiabatic compression. The correct answer is: an isothermal expansion, an adiabatic expansion, an isothermal compression and an adiabatic compression. Axo kg block slides on a rough surface; just before it hits a spring with constant 1693 N/m, is speed is 4.0 m/s; it compresses the spring by 5.0 cm before it comes to rest. The increase in internal energy is: N.B. Give your answer in Joules, do not put unit next to your answer. Amswer: 34 The correct answer is: 5.88375 The kinetic energy of a spring-mass system as a function of position (KE: vertical axis; x-horizontal axis) is best represented as: a ) C d e > > Select one: © Graph a) is the best representation Graph b) is the best representation Graph c) is the best representation Graph d) is the best representation Graph e) is the best representation The correct answer is: Graph c) is the best representation Question 33 ‘Mark 4.00 out of 4.00 & Flag question Question 34 ‘Mark 0.00 out of 4.00 © Flag question An ideal gas performs 20 J of work in an isothermal expansion where its volume increases from 10 liter to 20 liter; the work done by the same gas when its volume increases from 10 to 38 liter is: Answer: 38.52 The correct answer is: 38.520120779495 A U-tube is partially filled with water; oil of density 800 kg/m? is poured into one arm until the water level in the other arm rises by h = 2.1 cm; the height of the oil column is: N.B. Give your answer in cm, do not put the unit next to your answer. Answer: 2.625 The correct answer is: 5.25