Midterm practice

midterm study guide
Multiple Choice
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1. In the steps of the scientific method, what is the next step after formulating and objectively testing
hypotheses?
a. interpreting results b. stating conclusions c. conducting experiments d. making observations and
collecting data
2. The radius of Earth is 6 370 000 m. Express this measurement in km in scientific notation with the correct
number of significant digits.
a. km b. km c. km d. km
____ 3. Three values were obtained for the mass of a metal bar: 8.83 g; 8.84 g; 8.82 g. The known mass is 10.68 g.
The values are
a. accurate. b. precise. c. both accurate and precise. d. neither accurate nor precise.
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4. Which of the following equations best describes the graph above?
a. y = x + 1 b. y = x – 1 c. y = –x + 1 d. y = –x – 1
____ 5. Which of the following expressions gives units of kg m s ?
a. m x ( t) b. m ( x) ( t) c. m ( x) t d. ( t) m ( x)
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6. Which of the following units is the SI unit of velocity?
a. meter b. meter second c. meter per second d. second per meter
7. A baseball catcher throws a ball vertically upward and catches it in the same spot as it returns to the mitt. At
what point in the ball’s path does it experience zero velocity and nonzero acceleration at the same time?

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a. midway on the way up b. at the top of its path c. the instant it leaves the catcher’s hand d. the instant
before it arrives in the catcher’s mitt
8. Which of the following is a physical quantity that has a magnitude but no direction?
a. vector b. scalar c. resultant d. frame of reference
9. A football player runs in one direction to catch a pass, then turns and runs twice as fast in the opposite
direction toward the goal line. Which of the following is a correct expression for the original velocity and the
resulting velocity?
a. –v player , –2v player b. v player , 2v player c. v player , –2v player d. 2v player , –v player
____ 10. Which of the following is the tendency of an object to maintain its state of motion?
a. acceleration b. inertia c. force d. velocity
____ 11. A waitperson carrying a tray with a platter on it tips the tray at an angle of 12 below the horizontal. If the
gravitational force on the platter is 5.0 N, what is the magnitude of the force parallel to the tray that tends to
cause the platter to slide down the tray? (Disregard friction.)
a. 0.42 N b. 1.0 N c. 4.9 N d. 5.0 N
____ 12. The statement by Newton that for every action there is an equal but opposite reaction is which of his laws of
motion?
a. first b. second c. third d. fourth
____ 13. A sled weighing 1.0 10 N is held in place on a frictionless 20.0 slope by a rope attached to a stake at the
top. The rope is parallel to the slope. What is the normal force of the slope acting on the sled?
a. 94 N b. 47 N c. 37 N d. 34 N
____ 14. A crate is carried in a pickup truck traveling horizontally at 15.0 m/s. The truck applies the brakes for a
distance of 28.7 m while stopping with uniform acceleration. What is the coefficient of static friction between
the crate and the truck bed if the crate does not slide?
a. 0.400 b. 0.365 c. 0.892 d. 0.656
____ 15. In which of the following sentences is work used in the everyday sense of the word?
a. Lifting a heavy bucket involves doing work on the bucket. b. The force of friction usually does negative
work. c. Sam and Rachel worked hard pushing the car. d. Work is a physical quantity.
____ 16. Which of the following formulas would be used to directly calculate the kinetic energy of an object with mass
m bouncing up and down on a spring with spring constant k?
a. b. c. d.
____ 17. What are the units for a spring constant?
a. N b. m c. N m d. N/m
____ 18. If the displacement of a horizontal mass-spring system was doubled, the elastic potential energy in the system
would change by a factor of
a. 1/4. b. 1/2. c. 2. d. 4.
____ 19. Which of the following equations is not an equation for power, P, in terms of work, W, displacement, d, time
interval, t, force, F, and/or velocity, v?
a. b. c. d.
____ 20. Which of the following are not units of power?
a. hp b. J c. W d. J s

____ 21. A roller coaster climbs up a hill at 4 m/s and then zips down the hill at 30 m/s. The momentum of the roller
coaster
a. is greater up the hill than down the hill. b. is greater down the hill than up the hill. c. remains the same
throughout the ride. d. is zero throughout the ride.
____ 22. A billiard ball collides with a second identical ball in an elastic head-on collision. What is the kinetic energy
of the system after the collision compared with the kinetic energy before the collision?
a. unchanged b. one-fourth as great c. two times as great d. four times as great
____ 23. A ball is whirled on a string, then the string breaks. What causes the ball to move off in a straight line?
a. centripetal acceleration b. centripetal force c. centrifugal force d. inertia
____ 24. If you lift an apple from the ground to some point above the ground, the gravitational potential energy in the
system increases. This potential energy is stored in
a. the apple. b. Earth. c. both the apple and Earth. d. the gravitational field between Earth and the
apple.
____ 25. How would the speed of Earth’s orbit around the sun change if Earth’s distance from the sun increased by 4
times?
a. It would increase by a factor of 2. b. It would increase by a factor of 4. c. It would decrease by a factor
of 2. d. The speed would not change.
____ 26. A water bed that is 1.5 m wide and 2.5 m long weighs 1055 N. Assuming the entire lower surface of the bed
is in contact with the floor, what is the pressure the bed exerts on the floor?
a. 250 Pa b. 260 Pa c. 270 Pa d. 280 Pa
____ 27. What does the difference between gauge pressure and absolute pressure equal?
a. the pressure within the fluid b. the pressure at the surface of the fluid c. the pressure at the bottom of
the fluid d. zero
____ 28. The gauge pressure for the air in a balloon equals 1.01 10 Pa. If atmospheric pressure is equal to 1.01
10 Pa, what is the absolute pressure of the air inside the balloon?
a. 0 Pa b. 5.05 10 Pa c. 1.01 10 Pa d. 2.02 10 Pa
____ 29. If the flow rate of a liquid is measured at 8.0 10 m /s going through a 20.0 m radius pipe, which of the
following is the average fluid velocity in the pipe?
a. 4.0 10 m/s b. 0.64 m/s c. 2.0 m/s d. 6.4 m/s
____ 30. A water tunnel has a circular cross section where the diameter diminishes from 3.6 m to 1.2 m. If the velocity
of water is 3.0 m/s in the larger part of the tunnel, what is the velocity of water in the smaller part of the
tunnel?
a. 9.0 m/s b. 18 m/s c. 27 m/s d. 54 m/s
____ 31. Which of the following is proportional to the kinetic energy of atoms and molecules?
a. elastic energy b. temperature c. potential energy d. thermal equilibrium
____ 32. Which of the following is a form of kinetic energy that occurs within a molecule when the bonds are stretched
or bent?
a. translational b. rotational c. vibrational d. internal
____ 33. What are the energies associated with atomic motion called?
a. kinetic energy b. potential energy c. bond energy d. internal energy
____ 34. The use of fiberglass insulation in the outer walls of a building is intended to minimize heat transfer through
what process?

a. conduction b. radiation c. convection d. vaporization
____ 35. Which of the following describes a substance in which the temperature and pressure remain constant while
the substance experiences an inward transfer of energy?
a. gas b. liquid c. solid d. substance undergoing a change of state
____ 36. Which of the following is a thermodynamic process in which a system returns to the same conditions under
which it started?
a. an isovolumetric process b. an isothermal process c. a cyclic process d. an adiabatic process
____ 37. Which of the following is not a way in which a cyclic process resembles an isothermal process?
a. Energy can be transferred as work. b. Energy can be transferred as heat. c. The temperature of the
system remains constant throughout the process. d. There is no net change in the internal energy of the
system.
____ 38. Which equation describes the net work done for a complete cycle of a heat engine?
a. W = Q U b. W = Q Q c. W = Q Q d. W = P V
____ 39. Imagine you could observe the individual atoms that make up a piece of matter and that you observe the
motion of the atoms becoming more orderly. What can you assume about the system?
a. It is gaining thermal energy. b. Its entropy is increasing. c. Its entropy is decreasing. d. Positive work
is being done on the system.
____ 40. A chunk of ice with a mass of 1 kg at 0°C melts and absorbs 3.33 10 J of heat in the process. Which best
describes what happened to this system?
a. Its entropy increased. b. Its entropy decreased. c. Its entropy remained constant. d. Work was
converted to energy.
Short Answer
41. Convert g to kilograms using scientific notation.
42. What quantity describes the difference between an object’s initial position and the object’s final position?
43. What is the SI unit of acceleration?
44. Why is the direction of free-fall acceleration usually negative?

The figure above shows the path of a ball tossed from a building. Air resistance is ignored.
45. In the figure above, what would happen to the height of the ball’s path if it were launched with a lesser
velocity?
46. If two teams playing tug-of-war pull on a rope with equal but opposite forces, what is the net external force on
the rope?
47. In the following sentence, is the everyday meaning or the scientific meaning of work intended?
A bulldozer does work lifting a load.
48. What formula can be used to calculate work if the force acts at an angle to the displacement?
49. You are analyzing the flight of a projectile through the air. What assumption do you have to make in order to
use conservation of mechanical energy in your analysis?
50. Two snowballs are traveling straight toward each other. One snowball has twice the mass of the other, but is
moving at half the speed. The snowballs meet head-on in a perfectly inelastic collision. What is the total
momentum of the system containing the two snowballs before the collision?
51. Two horses are side by side on a carousel. Which has a greater tangential speed—the one closer to the center
or the one farther from the center? Explain your answer.
52. Use the concept of mechanical advantage to explain why, in a hydraulic lift, the smaller piston is pushed
down a farther distance than the larger piston is raised.
53. How does Archimedes’ principle relate to changes in pressure with depth?
54. What does Bernoulli’s principle state will happen to the pressure in a fluid as the speed of the fluid increases?
55. A pan of water at a temperature of 80 C is placed on a block of porcelain at a temperature of 15 C. What can
you state about the temperatures of the objects when they are in thermal equilibrium?
56. What is the specific heat capacity of a substance?
57. A physics textbook is balanced on top of an inflated balloon on a cold morning. As the day passes, the
temperature increases, the balloon expands, and the textbook rises. Is there a transfer of energy as heat? If so,
what is it? Has any work been done? If so, on what?
58. According to the first law of thermodynamics, how can the internal energy of a system be increased?

59. How is the conservation of a system’s internal energy mathematically expressed for an isothermal process?
Explain your answer.
60. Use the second law of thermodynamics and the equation for heat engine efficiency to show why efficiency
must always be less than 1.
Problem
61. A stroller walks the first half of a straight 1.4 km trail at a steady pace of 1.7 m/s, east. He walks the second
half at a constant stride of 0.37 m/s, east. What is his average velocity along the trail?
62. While grazing, a caribou treks 136 m at 53.0 west of south, and then 129 m west. What is the caribou’s
resultant displacement?
63. A sled is pulled at a constant velocity across a horizontal snow surface. If a force of 4.0 10 N is being
applied to the sled rope at an angle of 11 to the ground, what is the magnitude of the force of friction of the
snow acting on the sled?
64. Water flows over a section of Niagara Falls at a rate of 1.30 10 kg/s and falls 49.5 m. What is the power of
the waterfall?
65. A swimmer with a mass of 59 kg dives off a raft with a mass of 400 kg. If the swimmer’s speed is 3 m/s
immediately after leaving the raft, what is the speed of the raft?
66. Two ice-skaters, each with a mass of 50.0 kg, are stationary on a frictionless ice pond. One skater throws a
0.90 kg ball with a speed of 2.0 m/s to the other skater, who catches it. What are the velocities of the skaters
when the ball is caught?
67. A 4.2 m board with a mass of 19 kg is pivoted at its center of gravity. A helium balloon attached 0.24 m from
the left end of the board produces an upward force of 7.1 N. A 3.5 kg book is placed 0.74 m from the left end
of the board, and another book of 1.7 kg is placed 0.77 m from the right end of the board. Find the torque on
the board and the direction of rotation.
68. A block of wood has a density of 0.820 g/cm and dimensions of 19.0 cm, 9.0 cm, and 4.0 cm. How large a
force will just submerge the block in a vat of oil with a density 0.920 g/cm ?
69. What is the increase in the internal energy per kilogram of water at the bottom of a 115 m waterfall, assuming
that all of the initial potential energy is transferred as heat to the water? (g = 9.81 m/s )
70. The piston and flywheel part of a steam engine takes in 993 J of energy as heat and expels 514 J of energy as
heat. The internal energy of the system increases by 372 J during the process. Work is done by steam at a
pressure of 2.21 10 Pa. If the radius of the piston is 4.14 10 m, how far is the piston displaced?