CP Physics 36-Week Practice Exam Answers
1. A vector is a quantity that has magnitude and direction. (Definition)
D=Vavet
2.
=(75 m/s)(2s)=
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150 m
3. A volleyball player jumps up to spike a ball. Once her feet are off the floor, the player’s
acceleration equals “g” directed downward.
4.
T=∆V/A
=(52 m/s)/(4 m/s/s)=
13 sec
5.
D=1/2gt2
=1/2(10m/s/s)(.4s)2
=.8 m
6.
both the same, Galileo’s Law of Falling Bodies
7. Physics is the most basic science because it is all about the nature of basic things like forces,
energy, and motion, the ideas of physics extend into more complex sciences, underneath
biology is chemistry and underneath chemistry is physics, and you can better understand
science in general if you understand physics.
8.
g and downward-gravity causes the acceleration and gravity always works downward.
9.
A=∆V/t
10.
Vave=∆d/t
11.
=(45 m/s)/ 9 s
=600 km/8 hrs
=5 m/s/s
=75 km/hr
about 10 m/s/s-Gravity causing the acceleration is always about 10 m/s/s
12. The horizontal component of a projectile’s velocity and the vertical component of the
velocity are independent of each other. (definition)
13. When you look at the speedometer in a moving car, you can see the instantaneous speed?Defintion
14. 70 degrees-Complementary angles (add to 90) have the same horizontal range
15. Speed is always measured in terms of a unit of distance divided by a unit of time, a
measure of how fast something is moving, and the distance covered per unit of time.
16. about 10
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CP Physics 36-Week Practice Exam Answers
17.
c=Square root (x2 + y2)
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=Square root (52 + 122)= =a 13- unit vector
18. To test a scientific hypothesis, you would set up many experiments and look at the results
19. Acceleration is defined as the CHANGE in the velocity divided by the time interval
20. The penny, because the feather will encounter air resistance.
21. In the absence of air resistance, objects fall at a constant acceleration? Galileo’s Law of
Falling Bodies
22.
v=gt
=(10 m/s/s) (8 Sec)
=80 m/s
23. A scalar is a quantity that has magnitude only.
24. The following steps are a part of the Scientific methoda. recognize the problem
b. make a guess about the answer and predict its consequences (hypothesis)
c. predict the consequences of the hypothesis
d. perform experiments to test the predictions
e. formulate a general rule based on the predictions and experimental outcome
25. Anything that is moving through space that is affected only by gravity
26. The two measurements necessary for calculating average speed are distance and time
27.
Vave=∆d/t
=80 km/2hrs
=40 km/hr
28. zero, Galileo’s law of inertia
29. While an object near the earth’s surface is in free fall, its velocity increases.
30. The same time, because of Galileo’s Law of Falling Bodies
31. The juice container has inertia, keeping it at rest.
32. The snowmobile has inertia (continues moving with constant velocity unless an outside
force acts on it)
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CP Physics 36-Week Practice Exam Answers
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33. The object will continue moving at constant velocity (Newton’s First Law, body in motion
will continue in motion at a constant speed in a straight line unless some outside force acts
on it)
34. Kilograms measure mass (or inertia)
35. Weight is the gravitation attraction (force) between an object and the earth.
36. Twice as much mass means twice as much inertia.
37. Mass is the same (everywhere)
38. Force is measured in Newtons
39. Weight is measured in Newtons (it is a force)
40. Force is a vector because both its magnitude and direction are important.
41. Acceleration would be tripled. Force and Acceleration are directly proportional.
42. Acceleration is 1/4x. Mass and Acceleration are inversely proportional.
43. Net Force =5 N (forces in opposite direction so subtract)
44. Net Force =0 N (same reason as 43)
45. Acceleration =0 m/s/s (A=F/M)
46. 19.6 N or 20 N (weight=Mass x gravity)
47. 4500 N (F=MA = 1500 kg x 3 m/s/s)
48. 2000 kg (M=F/A = 4000 N/ 2 m/s/s)
49. 4 m/s/s (A=F/M = 20 N/5 kg)
50. No force is needed to keep an object moving in outer space at constant velocity (no
outside forces to stop it)
51. 300 N (weight is evenly distributed between the 2 scales)
52. At the top of its path, the ball stops so the speed is zero. The acceleration of an object in
the air is always g or 9.8 m/s/s.
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CP Physics 36-Week Practice Exam Answers
53. Arrow against the bowstring.
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54. 500 N (Newton’s third law=forces equal and opposite)
55. Same on both. (Newton’s third law says forces equal and opposite)
56. Pickup truck speeding on highway. (Building and parked truck have v=0 m/s so no
momentum, dog and tightrope walker have small mass, so momentum=small)
57. Buckshot is much lighter than the shotgun, so the speed of the shotgun is much smaller
(since their momentums will be equal and opposite)
58. The force is reduced because the time of impact is increased (F=m∆v/∆t)
59. Force is 1/10 because the force and time are inversely proportional.
60. There is an increased time of impact on the driver which reduces the impact force (see
#58)
61. Work=Force x distance
62. Work=Force x distance Since force and distance are tripled, the work is 9x as high (3x3)
63. the change in potential energy of an elevated object is equal to the work done in lifting
the object.
64. KE=1/2 mass x Velocity2
65. Kinetic energy is energy of motion, potential energy is the energy of position (location).
66. Conservation of Energy states that no energy is lost or gained, so 100 Joules
67. Conservation of Energy states that the total amount of energy remains the same. Since at
the bottom there is no potential energy, all is kinetic. KE=10,000 J
68. Power (rate that work is being done) P=W/t
69. Kinetic Energy =1/2 mass x velocity2, so it is directly proportional to the square of the
velocity. If the velocity triples, the KE is multiplied by 32 or 9x as great.
70. Work=force x distance. Since the force is not moving a building, no work is done.
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CP Physics 36-Week Practice Exam Answers
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71. P=W/t (Power is inversely proportional to time) so Joe is doing the same work with 2x the
power.
72. They are equal (PE=KE=5000 J)
73. Using either Newton’s Law of Universal gravity or Newton’s third Law, both forces are
equal.
74. Force is inversely proportional to distance squared (inverse square law) so as the distance
gets bigger (further away), the force gets smaller.
75. Gravitational forces are relatively small between objects. They are only large when
dealing with very large masses.
76. Conduction, convection, and radiation.
77. Good conductors of heat are bad insulators of heat.
78. Convection occurs in fluids (liquids and gases)
79. Good absorbers are also good emitters (radiators)
80. Black-Black is a good absorber and a good emitter. White reflects.
81. Same answer as 80.
82. Gravitational forces are comparatively small. Electrical forces can repel or attract.
83. Electrical forces obey the inverse square law. As they get closer (distance decreases), the
force between them increases.
84. Electrical forces obey the inverse square law. As they get closer (distance decreases), the
magnitude of the force between them increases. For oppositely charged, the value gets
more negative, but the force itself is greater.
85. Like charges repel. Opposite charges attract.
86. Protons are positive, electrons are negative. They are opposites.
87. The electric field inside of the shed (metal) is zero.
88. Doubling the distance reduces the force by ¼ (inverse square law)
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CP Physics 36-Week Practice Exam Answers
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89. Electrical forces are relatively large (they appear small because you are usually dealing
with small amounts of charge)
90. They are both inversely proportional to the square of the distance between them.
91. Resistance=Ohms, Current=Amperes (Amps), Power=Watts
92. I=V/R = 220 Volt/20 ohm = 11 Amps
93. The resistance gets larger as the resistor gets wider. The resistance also gets larger as the
object gets smaller. Both would make the resistance larger.
94. P= I V = 4 Amp x 120 Volt = 480 Watt
95. A series circuit is one where the current is continuous through all resistors so that if one
resistor breaks (light bulb goes out), they current is stopped and all resistors go out.
96. A parallel circuit is one where each branch of a circuit has the same potential. Each
branch is independent of each other. Current only stops to the resistor that breaks.
97. P = I2 R = (5 Amp )2 x (5 Ohm)
=125 Watts
98. AC circuits utilize electrons that are already on the element and force them back and
forth. Therefore, the filament uses electrons that are already on the filament.
99. Period is the time for 1 wave cycle.
100. Wavelength=distance between successive identical parts of a wave (or distance between
2 crests/troughs)
Frequency=# of waves that pass a point each second
Node=point on the wave with no amplitude
Crest=top of the wave
Trough=bottom of the wave
101. Interference occurs when two waves overlap
102. Constructive interference is when the amplitudes of the wave match up and are added
together creating a bigger wave
Destructive interference is when the amplitudes of the wave are out of phase and take away
from one another creating a smaller wave.
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CP Physics 36-Week Practice Exam Answers
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103. Frequency is the inverse of the period. If you triple the frequency, the period is 1/3.
104. A wave travels one wavelength in one period.
105. T=1/f = 1/.2 Hz=5 sec
106. Sound is a longitudinal wave.
107. Any electromagnetic wave is a transverse wave. (light, microwaves, IR, UV, gamma rays
etc)
108. Sound cannot travel in a vacuum. Light can travel in a vacuum. Sound needs a medium.
Light does not (as evidence, the sun’s rays reach earth)
109. Sound travels fastest through solids and slowest through gases.
110. λ=v/f = 340 m/s / 170 Hz = 2 meters
111. The Doppler effect occurs when the source OR the receiver of sound is moving towards
or away from each other.
112. The frequency of sound determines the pitch of sound.
113. As the source of sound approaches the receiver, the frequency (pitch) is higher and the
wavelength smaller. As the source of sound recedes, the frequency is lower and the
wavelength is larger.
114. Ultrasonic (frequency is too high for humans to hear)
115. Supersonic (travels faster than the speed of sound)
116. Resonance is when an object is forced to vibrate at its natural frequency.
117. Resonance caused the glass to shatter.
118. The result is a beat frequency of 4 Hz. (beat=periodic constructive and destructive
interference)
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CP Physics 36-Week Practice Exam Answers
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119. Some examples of electromagnetic waves are Microwaves, radio waves, x rays, gamma
rays, UV, IR, visible light.
120. Waves transmit energy, not matter. This is demonstrated by a boat on the ocean merely
goes up and down when a wave passes and is not pushed from side to side.
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