Final Exam Review PHYS 1401 - Brooks Chapters 8-14 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A uniform rod has a length of 2.0 m. It is hinged to a wall (at the left end), and held in a horizontal position by a vertical massless string (at the right end), as shown in Figure 8-8. Figure 8-8

What is the angular acceleration of the rod at the moment the string is released? A) 15. rad/s2

B) 11. rad/s2 C) 3.3 rad/s2 D) 7.4 rad/s2

E) It can't be calculated without knowing the rod's mass.

Answer: D

Page Ref: Sec. 8.3

2) Consider two equal mass cylinders rolling with the same translational velocity. The first cylinder (radius = R) is hollow and has a moment of inertia about its rotational axis of M R2 , while the second cylinder (radius = r) is solid and has a moment of inertia about its axis of 0.5 M r2 . What is the ratio of the hollow cylinder's angular momentum to that of the solid cylinder?

A) 2R to r

B) R to 2r

C) 2R2 to r2

D) r to 2R

E) r2 to 2R2

Answer: A

Page Ref: Sec. 8.5

3) A heavy boy and a lightweight girl are balanced on a massless seesaw. If they both move forward so that they are one-half their original distance from the pivot point, what will happen to the seesaw? A) The side the girl is sitting on will tilt downward. B) The side the boy is sitting on will tilt downward. C) Nothing, the seesaw will still be balanced. D) It is impossible to say without knowing the masses of the children. E) It is impossible to say without knowing the values of the original distances. Answer: C

Page Ref: Sec. 8.2

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4) An object's angular momentum changes by 10 kg-m 2 /s in 2.0 s. What magnitude average torque acted on this object? A) 20 N-m B) 40 N-m C) 5 N-m D) 10 N-m E) 2.5 N-m Answer: C

Page Ref: Sec. 8.5

5) What condition or conditions is/are necessary for static equilibrium? A) Fx = 0, Fy = 0 B) Fx = 0, Fy = 0, C) Fy = 0

=0

D) Fx = 0 E) =0 Answer: B

Page Ref: Sec. 8.2

6) A hoop of radius 0.50 m and a mass of 0.20 kg is released from rest and allowed to roll down an inclined plane. How fast is it moving after dropping a vertical distance of 3.0 m? A) 7.7 m/s B) 5.4 m/s C) 3.8 m/s D) 6.2 m/s E) 2.2 m/s Answer: B

Page Ref: Sec. 8.4

7) Consider two uniform solid spheres where one has twice the mass and twice the diameter of the other. The ratio of the larger moment of inertia to that of the smaller moment of inertia is A) 8. B) 2. C) 4. D) 6. E) 10. Answer: A

Page Ref: Sec. 8.3

8) An ice skater performs a pirouette (a fast spin) by pulling in his outstretched arms close to his body. What happens to his angular momentum about the axis of rotation? A) It does not change. B) It decreases. C) It changes, but it is impossible to tell which way. D) It increases. Answer: A

Page Ref: Sec. 8.5

9) A ball, solid cylinder, and a hollow pipe all have equal masses and radii. If the three are released simultaneously at the top of an inclined plane, which will reach the bottom first? A) they all reach bottom in the same time B) cylinder C) pipe D) ball Answer: D

Page Ref: Sec. 8.4

10) A wheel of moment of inertia of 5.00 kg-m 2 starts from rest and accelerates under a constant torque of 3.00 N-m for 8.00 s. What is the wheel's rotational kinetic energy at the end of 8.00 s? A) 57.6 J B) 78.8 J C) 91.9 J D) 122.0 J E) 64.0 J Answer: A

Page Ref: Sec. 8.4

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11) When you are scuba diving, the pressure on your face plate A) will be greatest when you are facing upward. B) depends only on your depth, and not on how you are oriented. C) is independent of both depth and orientation. D) will be greatest when you are facing downward. Answer: B

Page Ref: Sec. 9.2

12) A ship that weighs 10,000 tons (mass 10 million kg) must displace what volume of fresh water in order to float? A) 1012 m 3 B) 107 m 3 C) 108 m 3 D) 1010 m 3 E) 104 m 3 Answer: E

Page Ref: Sec. 9.3

13) Water flows through a horizontal pipe of cross-sectional area 10. cm2 at a pressure of 0.25 atm. The flow rate is 1.0 L/s. At a valve, the effective cross-sectional area of the pipe is reduced to 5.0 cm2. What is the pressure at the valve? A) 7.7 × 103 Pa B) 0.157 atm C) 0.200 atm D) 0.112 atm E) 0.235 atm Answer: E

Page Ref: Sec. 9.4

14) The internal energy of an ideal gas depends on A) its volume. B) its temperature and pressure. C) its pressure. D) its temperature, pressure, and volume. E) its temperature. Answer: E

Page Ref: Sec. 10.5

15) On a winter -3.° C morning, the pressure in a car tire reads 28. psi on a pressure gauge. After several hours of highway traveling, the pressure reads 35. psi. Assuming the volume remains constant and normal atmospheric pressure of 15. psi, what is the tire temperature? A) 45° C B) 55° F C) 25° C D) 41° C E) 55° C Answer: D

Page Ref: Sec. 10.3

16) Which two temperature changes are equivalent? A) -40 C°, -40 F° B) 1 K, 1 F°

C) 1 F°, 1 C°

D) 1 C°, 1 K

Answer: D

Page Ref: Sec. 10.3

17) A lamp radiates 75. J/s when the room is set on 27°C but it radiates 90. J/s when the room temperature drops to 10. C. What is the temperature of the lamp? A) 97. K B) 97.° C C) 86.° C D) 110.° C E) 86. K Answer: C

Page Ref: Sec. 11.4

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18) Phase changes occur with an attendant A) temperature decrease. C) temperature increase.

B) temperature remaining constant. D) convection.

Answer: B

Page Ref: Sec. 11.3

19) If you double the absolute temperature of an object, it will radiate energy A) 16 times faster. B) 2 times faster. C) 8 times faster.

D) 4 times faster.

Answer: A

Page Ref: Sec. 11.4

20) Steam will burn the skin more severely than boiling water because of water's relatively large A) conductivity. B) emmisivity. C) compressibility. D) specific heat. E) latent heat. Answer: E

Page Ref: Sec. 11.3

21) A large fan placed in a closed room is effective by enhancing A) sublimation. B) conduction. C) radiation. Answer: D

Page Ref: Sec. 11.4

22) You blow on food to cool it. Blowing increases A) conduction. B) the specific heat. C) radiation. D) the latent heat. E) convection. Answer: E

Page Ref: Sec. 11.4

23) The second law of thermodynamics leads us to conclude that A) it is theoretically possible to convert heat into work with 100% efficiency. B) disorder in the universe is increasing with the passage of time. C) the average temperature of the universe is increasing with the passage of time. D) the total energy of the universe is constant. Answer: B

Page Ref: Sec. 12.4

24) When water freezes, the entropy of the water A) decreases. B) could either increase or decrease; it depends on other factors. C) does not change. D) increases. Answer: A

Page Ref: Sec. 12.4

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D) convection.

25) A Carnot cycle consists of A) two isobars and two isotherms. B) two adiabats and two isotherms. C) two isotherms and two isomets. D) four adiabats. E) two adiabats and two isobars. Answer: B

Page Ref: Sec. 12.6

26) A gas is confined to a rigid container that cannot expand as heat energy is added to it. This process is A) isobaric. B) isometric. C) isothermal. D) adiabatic. E) isentropic. Answer: B

Page Ref: Sec. 12.3

27) When the first law of thermodynamics, Q = u + W, is applied to an ideal gas that is taken through an isothermal process, A) u = 0. B) W = 0. C) P = 0. D) Q = 0. Answer: A

Page Ref: Sec. 12.3

28) A certain amount of a monatomic gas is maintained at constant volume as it is cooled by 50 K. This feat is accomplished by removing 400 J of energy from the gas. How much work is done by the gas? A) 200 J B) 400 J C) zero D) -400 J E) -200 J Answer: C

Page Ref: Sec. 12.2

29) What mass should be attached to a vertical spring (k = 39.5 N/m) so that the natural vibration frequency of the system will be 1.00 Hz? A) 39.5 kg B) 1.00 kg C) 6.29 kg D) 2.00 kg E) 1.56 kg Answer: B

Page Ref: Sec. 13.2

30) Doubling only the amplitude of a vibrating mass-and-spring system produces what effect on the system's mechanical energy? A) increases the energy by a factor of two B) produces no change C) increases the energy by a factor of four D) increases the energy by a factor of 2 E) increases the energy by a factor of three Answer: C

Page Ref: Sec. 13.1

31) A 2-kg mass is hung from a spring (k = 18 N/m), displaced slightly from its equilibrium position, and released. What is the frequency of its vibration? A) 1.5 Hz B) 1.5/ Hz C) 1.5 Hz D) 3.0/ Hz E) 3.0 Hz Answer: B

Page Ref: Sec. 13.2

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32) What is the amplitude (in meters) of a wave whose displacement is given by y = 50. sin(0.20x + 120t) cm? A) 0.50 m B) 6 m C) 0.20 m D) 10 m E) 1.0 m Answer: A

Page Ref: Sec. 13.3

Consider the wave shown in Figure 13-5 below for the following item(s). Figure 13-5

33) The wavelength in Figure 13-5 A) is 4 m. B) is 8 m. C) is 2 m. D) cannot be determined from the given information. Answer: D

Page Ref: Sec. 13.3

34) If the intensity of sound changes (increases) by a factor of 100, the decibel level changes by a factor of A) 20. B) 100. C) log 100. D) 10. E) 1. Answer: A

Page Ref: Sec. 14.3

35) If you hear thunder 5.0 s after seeing a flash of lightning, the distance to the lightning strike is about A) 0.90 km. B) 1.7 km. C) 0.60 km. D) 2.2 km. E) 1.2 km. Answer: B

Page Ref: Sec. 14.2

36) What happens to the velocity of sound in a gas when the absolute temperature of that gas is doubled? A) It doubles. B) It quadruples. C) It increases to 1.41 times its original value. D) It stays the same. Answer: C

Page Ref: Sec. 14.2

37) How many decibels correspond to a sound intensity of 7.0 × 10-7 W/m2 ? A) 75 B) 69 C) 58 D) 70 Answer: C

Page Ref: Sec. 14.3

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E) 63

38) A force is applied to the end of a 2.0 ft long uniform board weighing 50. lb, in order to keep it horizontal, while it pushes against a wall at the left. If the angle the force makes with the board is 30° in the direction shown in Figure 8-6, what is the applied force F? Figure 8-6

A) 32. lb

B) 50. lb

C) 29. lb

D) 90. lb

E) 58. lb

Answer: B

Page Ref: Sec. 8.2

39) Consider a rigid body that is rotating. Which of the following is an accurate statement? A) Its center of rotation must be at rest, i.e., not moving. B) All points on the body are moving with the same linear velocity. C) All points on the body are moving with the same angular velocity. D) Its center of rotation is its center of gravity. E) Its center of rotation must be moving with a constant velocity. Answer: C

Page Ref: Sec. 8.1

40) "Pressure applied to an enclosed fluid is transmitted to every point in the fluid and to the enclosure walls" is known as A) Archimedes' principle. B) Kepler's law. C) Fermet's principle. D) Bernoulli's principle. E) Pascal's principle. Answer: E

Page Ref: Sec. 9.2

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41) The slope of the straight line shown on the graph in Figure 9-1 is called the Figure 9-1

A) compressibility.

B) bulk modulus.

C) pressure.

D) Young's modulus.

Answer: D

Page Ref: Sec. 9.1

42) The volume coefficient of thermal expansion for gasoline is 9.50 × 10-4 per degree C. By how much does the volume of 1 L of gasoline change when the temperature rises from 20.°C to 40.°C? A) 6.0 cm3 B) 24. cm3 C) 12. cm3 D) 37. cm3 E) 19. cm3 Answer: E

Page Ref: Sec. 10.4

43) Two equal mass objects (which are in thermal contact) make up a system that is thermally isolated from its surroundings. One object has an initial temperature of 100°C and the other has an initial temperature of 0°C. What is the equilibrium temperature of the system, assuming that no phase changes take place for either object? (The hot object has a specific heat capacity that is three times that of the cold object.) A) 19°C B) 23°C C) 75°C D) 50°C E) 25°C Answer: C

Page Ref: Sec. 11.2

44) A Carnot engine is operated as a refrigerator, taking in 18. J of heat every second and expelling 20. J into a 23.°C room. What is the temperature inside the refrigerator? A) 3.0°C B) -15°C C) 15°C D) -6.6°C E) 300. K Answer: D

Page Ref: Sec. 12.6

45) An air conditioner with a coefficient of performance of 3.5 uses 30 kW of power. How much power is it discharging to the outdoors? A) 75 kW B) 105 kW C) 30 kW D) 135 kW E) 210 kW Answer: D

Page Ref: Sec. 12.5

46) Compare two vibrating strings, each has the same tension, but the second has four times the mass density of the first. The wave speed along the 2nd string is how many times the speed along the 1st? A) 4 B) 2 C) 2 D) 1/2 E) 1/4 Answer: D

Page Ref: Sec. 13.5

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47) The Doppler shift explains A) how sonar works. B) why the siren on a police car changes its pitch as it races past us. C) why it is that our hearing is best near 3000 Hz. D) why a sound grows quieter as we move away from the source. E) the phenomenon of beats. Answer: B

Page Ref: Sec. 14.5

48) A planet speeds up in its orbit as it gets closer to the sun because of A) conservation of energy. B) conservation of momentum. C) conservation of angular momentum. D) the torque exerted on the planet by the sun. E) inertia. Answer: C

Page Ref: Sec. 8.5

49) An ice skater performs a pirouette (a fast spin) by pulling in his outstretched arms close to his body. What happens to his moment of inertia about the axis of rotation? A) It decreases. B) It increases. C) It does not change. D) It changes, but it is impossible to tell which way. Answer: A

Page Ref: Sec. 8.5

50) A container of water is placed on a scale, and the scale reads 120. g. Now a 20.0g piece of copper (specific gravity = 8.90) is suspended from a thread and lowered into the water, not touching the bottom of the container. What will the scale now read? A) 122 g B) 120 g C) 112 g D) 140 g E) 138 g Answer: A

Page Ref: Sec. 9.3

51) An irreversible engine operating between the temperatures of 550 K and 300 K extracts 1200 J of heat from the hot reservoir and produces 450 J of work. How much entropy is created in the process? A) 0.44 J/K B) 0.68 J/K C) 0.32 J/K D) 0.73 J/K E) 0 J/K Answer: C

Page Ref: Sec. 12.4

52) A closed organ pipe of length 0.750 m is played when the speed of sound in air is 340. m/s. What is the fundamental frequency? A) 0.228 kHz B) 0.113 kHz C) 171. Hz D) 57.0 Hz E) 570. Hz Answer: B

Page Ref: Sec. 14.6

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53) A container is filled with a mixture of helium and oxygen gases. A thermometer in the container indicates that the temperature is 22.° C. Which gas molecules have the greater average speed? A) The helium molecules do because they are less massive. B) The helium molecules do because they are monatomic. C) The oxygen molecules do because they are more massive. D) The oxygen molecules do because they are diatomic. E) It is the same for both because the temperatures are the same. Answer: A

Page Ref: Sec. 10.5

54) 50 g of lead (c = 0.11 kcal/kg · °C) at 100°C is put into 75 g of water at 0°C. What is the final temperature of the mixture? A) 25°C B) 2°C C) 6.8°C D) 50°C Answer: C

Page Ref: Sec. 11.2

55) If you take a given pendulum to the moon, where the acceleration of gravity is less than on Earth, the resonant frequency of the pendulum will A) not change. B) increase. C) decrease. D) either increase or decrease; it depends on its length to mass ratio. Answer: C

Page Ref: Sec. 13.2

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