GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
Motion is the change of position in a certain amount of time. The motion of an object can be
measured by its speed. Speed is the distance traveled in an unit of time; it is the “rate of motion”.
To calculate speed,
Speed =

Distance
v=
d
Time
t
Speed can be described in 3 ways:
 Instantaneous – speed at a given instant  speedometer
 Constant – speed that does not change; moving at a steady pace
 Average – opposite of constant speed; total distance divided by the total time
Velocity describes the speed and direction of a moving object.
1.
2.
3.
Sample Problems
A car travels 240 km in 3 hours. What is the speed of the car during that time?
The speed of a cruise ship is 50 km/hr. How far will the ship travel in 14 hours?
Sound travels at a speed of 330 m/sec. If a lightning bolt strikes the ground 1000 m away
from you, how long will it takes for the sound to reach you?
A change in velocity in a unit of time is called acceleration. The velocity change may be due to
a change in speed, a change in direction, or both. To calculate acceleration,
Acceleration =
Change in velocity

a=
v
Time
t
Change in velocity (v) = Final velocity – Initial velocity
Generally, the unit for acceleration is m/sec2.


1.
2.
Positive acceleration  a moving object is “speeding up”
Negative acceleration (deceleration)  a moving object is “slowing down”
Sample Problems
A swimmer speeds up from 1.1 m/sec to 1.3 m/sec during the last 20 seconds of the
workout. What is the acceleration during that time?
A roller coaster is moving at 25 m/sec at the bottom of a hill. Three seconds later, it reaches
the top of the next hill, moving at 10 m/sec. What is the acceleration of the rolling coaster?
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
Momentum measures how strongly an object tends to keep moving; it asks “how hard it is to
stop a moving object?” To calculate momentum,
Momentum = Mass X Velocity
p=mXv
The unit for momentum is kg m/sec.Momentum depends on mass and velocity. The more mass
and/or more velocity a moving object has, the greater its momentum.
Sample Problem: What is the momentum of a 0.30 kg blue jay flying at 17 m/sec?
Law of Conservation of Momentum
When a collision occurs, the momentum of one object is transferred to another object.
Thus,
=
Total momentum
before collision
Total momentum after
collision
No matter how the two objects collide, the total momentum of the two objects is always the
same. Momentum is always conserved.
Sample Problems: Two train cars traveling in opposite directions will collide with each other
under the following conditions:
a)
b)
c)
d)
e)
Train Car
Mass
Velocity
A
10 kg
14 m/sec east
B
10 kg
10 m/sec west
What is the momentum of Train Car A?
What is the momentum of Train Car B?
What is the total momentum?
Which train car has more momentum? Explain.
The two train cars collide and stick together. In which direction do you think both cars will
move?
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
A force is a push or pull. It can also do the following:
 It can start or stop motion
 It can give energy to an object
 It can change the direction of a moving object
The unit for force is Newton (N).
Vectors
Velocity, acceleration, and momentum are examples of a vector quantity. A vector quantity is
anything that has magnitude (size, distance, or amount) and direction. These quantities can be
represented by arrows called vectors.
Same magnitude, different directions
Different magnitudes, same direction
Force is also a vector quantity and can be represented as a vector (or arrow). The length of the
vector represents the magnitude of the force, and the direction of the vector indicates the
direction of the force.
Combining Forces
We can use vectors to show how forces acting on an object can combine.
A. Adding forces – Combining forces in same direction
If more than one force are acting on an object in the same direction, then the forces are added
together.
1N
1 kg
1 kg

2N
mass
mass
1N
B. Subtracting forces – Combining forces in opposite directions
1. Balanced forces – When two equal forces are acting in opposite directions, the
forces cancel out each other.
1N
1 kg
mass
1N

0N
1 kg
mass
Thus, with balanced forces, there is no change in motion (i.e., the object is either
moving at a constant speed or not moving at all).
2. Unbalanced (Net) forces – When two forces of different magnitudes are acting in
opposite directions, the forces are subtracted. The direction of the resultant force
will be the same as that of the larger force.
2N
3N
1 kg
1 kg

mass
mass
Thus, an unbalanced (net) force can change the motion of an object.
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
Friction is a force opposing motion. It will cause a moving object to slow down and finally
stop. It occurs whenever two surfaces are touching each other. The amount of friction depends
on how hard the surfaces are forced together and on the materials of which the surfaces are
made.
When you exert a force on an object in one direction, friction will always act in the
opposite direction. Thus, to overcome friction, a larger force must be exerted.
Three types of friction
 Static – both objects are stationary
 Kinetic – both objects are in motion (sliding or rolling)
 Fluid – force exerted by a liquid or gas (example: air resistance)
Friction can be helpful or harmful.
Ways to decrease friction
 Lubricate the surfaces with motor oil, wax, grease, etc.
 Smooth the surfaces
 Place ball bearing between the surfaces
Newton’s Laws of Motion
1st Law:
2nd Law:
An object at rest will remain at rest and an object in motion will remain in
motion at constant velocity unless acted upon by an unbalanced force; also
called the “Law of Inertia”. [NOTE: An object in motion tends to always move
in a straight line.]
Force, mass, and acceleration are related.
Force = mass X acceleration  F = ma
Remember, the unit of force is Newton (N).
1 N = 1 kg X 1 m/sec2
NOTE: The acceleration of an object is directly proportional to the net (or applied) force on
the object and inversely proportional to the object’s mass.
TRENDS: Comparing two or more objects under the 2nd Law of Motion
1. The larger the mass, the greater the applied force  if the accelerations are the same
[Ex: one person rolling a 3-kg ball and a 6-kg ball down the street]
2. The larger the mass, the less it accelerates  if the applied forces are the same [Ex:
pushing an empty shopping cart and pushing a shopping cart full of groceries]
3. The greater the acceleration, the greater the force  if the masses are the same [Ex:
two identical cars  one person pushing one car; two persons pushing the other
car]
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
Sample Problems
1.
2.
3.
A 50-kg skater pushed by a friend accelerates 5 m/sec2. How much force did the friend
apply?
A bowling ball rolled with a force of 15 N accelerates at a rate of 3 m/sec2; a second ball
rolled with the same force accelerates at 4 m/sec2. Which ball do you think will have the
greater mass? To verify your answer, calculate the mass of each ball.
If a 60-kg person on a 15-kg sled is pushed with a force of 300 N, what will be the person’s
acceleration?
3rd Law:
For every action, there is an equal and opposite reaction; all forces come in
pairs.  ALL FORCES ACT IN PAIRS!
Some forces can be seen or felt; some forces cannot be seen or felt. Nevertheless, they are
present!
Gravity is a natural force of attraction that occurs between two (or more) objects. It exists
throughout the universe. Gravity depends on the masses of the objects and the distance between
them.
The bigger the object, the more
gravitational pull (gravity) it has
The closer the two objects are, the
greater the gravitational pull
between them
The further the two objects are, the
lesser the gravitational pull
between them
On Earth, the gravity pulls any falling object (excluding air resistance) toward the center of Earth
at the same rate  “free-fall”. The acceleration due to gravity (“free-fall”) is 9.8 m/sec2. That
means, on Earth, a falling object will accelerate to the ground at 9.8 m/sec2. Of course the freefall acceleration is different on other planets in the solar system. Some planets have higher/lower
gravitational pull than Earth.
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
MASS VS. WEIGHT  THE FORCE OF GRAVITY
Mass is the amount of matter an object has; weight is the amount of gravitational pull exerted on
an object. Since weight depends on gravity, it can change. Mass doesn’t ever change; it is
always constant.
Since weight is a force (SI Unit: Newton), we can calculate it as follows:
Weight = mass x gravity
W = mg
where the acceleration of gravity on Earth is 9.8 m/sec2.
Sample Problems
An astronaut has a mass of 66 kg.
a). Calculate his weight (in Newtons) on Earth.
b). Calculate his weight on the moon (gravity is 1.6 m/sec2).
c). Why did the weight of the astronaut change when he went to the moon?
d) Did his mass change? Why or why not?
Work has a common, everyday meaning, but it also has a scientific meaning. Work measures the
effects of force acting over a distance.
Work = force x distance
W=Fxd
The unit for work is called Joule (J)
1J=1Nx1m
Work is only done when force cause a change in the motion of an object.
Power measures the rate at which work is done. That is, how much work is done in a certain
amount of time?
Power = Work/time
P = W/t
The unit for power is called Watt (W)
1 W = 1 J/1 sec
Sample Problems
1. A father was playing with his daughter by lifting her repeatedly in the air. How much work
does he do with each lift, assuming he lifts her 2.0 m and exerts an average force of 190 N?
2. It takes 100,000 J of work to lift an elevator 18 m. If this is done in 20 seconds, what is the
power of the elevator during the process?
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
A machine is a device that makes work easier; it can change the size or the direction of the force
you exert. WITH OR WITHOUT A MACHINE, THE AMOUNT OF WORK DONE WILL
BE THE SAME!
There are six types of simple (basic) machines. They are divided into two groups:
The Lever Family
 Simple lever
 Pulley
 Wheel and axle
Simple Machine
A simple lever is a straight,
rigid bar that rest on a support
called a fulcrum
A pulley is a grooved wheel
with a rope or cable around it;
it’s a modified lever
A wheel and an axle is a
wheel with a rod (called an
axle) through its center; both
parts move together. It’s a
turning lever.
An inclined plane is a slanted
surface connecting a lower
level to a higher level
A wedge is made from two
inclined planes placed back to
back; it has at least one slanted
side and a sharp edge
A screw is an inclined plane
wrapped around a cylinder or
a pole
The Inclined Plane Family
 Inclined plane
 Wedge
 Screw
How does it make work
easier?
Lifts or moves things
Moves things up, down, and
across
Examples
Shovel, nutcracker,
screwdriver, broom, crowbar,
bottle opener, seesaw,
forearm, jack (car)
Curtain rod, tow truck, miniblind, flag pole, crane
Moves things; lifts things
Cars (steering wheels and tires
on the car), wagons, bicycles,
doorknob, pencil sharpener,
skateboard
Moves things up or down on it
Slide, stairs, ramp, escalators,
slope
Cuts or spread an object apart
Knife, pin, nail, chisel, ax,
snowplow, front of a boat
Holds things together or lifts
things
Screws, jar lids, bottle caps,
bottom of a light bulb,
corkscrew
A compound machine is made of two or more simple machines.
The mechanical advantage (MA) of a machine tells us how much a machine multiplies force or
distance; it describes how easier the machines get the work done. The larger the MA, the less
effort needed to get the work done. There are two types of MA – Ideal and Actual.
A. Ideal Mechanical Advantage (IMA)
 It is the MA of an ideal machine (the “perfect” machine which is frictionless)
 It is theoretical – “that’s what it is supposed to be”
 To calculate IMA,
IMA = Effort distance
Resistance distance
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
B. Actual Mechanical Advantage (AMA)
 It is the MA of a real machine
 It takes into consideration real world factors (i.e., friction and energy lost)
 To calculate AMA,
AMA = Resistance force
Effort force
Where,
 Effort force/distance – the force/distance applied by you to move an object
 Resistance force/distance – force/distance applied by the machine to overcome
resistance (weight of object being moved)
In this class and on future tests, unless otherwise it is stated that the machine is ideal, ALWAYS
ASSUME WE ARE DEALING WITH REAL MACHINES (SOLVE FOR AMA – even if
friction is ignored)!
For inclined planes,
Length
MA = length/height
Height
For simple levers,
MA = distance of the effort force from the fulcrum
distance of the resistance force from the fulcrum
Resistance force (load)
Effort force
Fulcrum
Where the effort force is the force YOU exert on the lever and the resistance force is the force
exerted on the object (can be the object’s weight)
For wheels and axles,
MA = radius of the wheel/radius of the axle
Wheel
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
For pulleys,
MA = # of rope segments pulling on the resistance force (load)
Resistance
force
(load)
Effort force
The efficiency of a machine compares the work output to the work input
Efficiency = Work Output x 100 %
Work Input
The amount of work done by the effort force is the work input. The amount of work done on the
resistance (load) is the work output. In the real world, because extra work must be done to
overcome friction, work input is always greater than work output.
Since extra work must be put into the machine to overcome friction, work output can never be
greater than work input. The efficiency of a machine can never be greater than 100 %; in fact,
there is no machine that is 100 % efficient since friction is always present.
Sample Problem: Jordan used a crowbar to open a crate. She applied a force of 10 N to the end
of a 30 cm (0.3 m) crowbar. The resistance of the crate lid was 40 N, and it opened 6 cm (0.06
m). [Assume friction is ignored]
a) What is the mechanical advantage?
b) What was the efficiency of the crowbar?
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
Energy – the ability to do work; SI Unit for energy is Joules (J)
Two States of Energy
Kinetic energy (KE) – energy of motion
Potential energy (PE) – energy of position; stored
 Any moving object has kinetic
energy
energy
An object with PE has the potential, or the ability, to
 KE depends on mass and velocity
do work or release energy
The more mass and/or velocity a moving
 PE stored in a spring, bungee cord, or rubber
object has, the greater its KE
band is called elastic PE
 PE from the height off the ground is called
To calculate KE,
gravitational PE – the higher the object is
KE = ½ mv2
off the ground, the greater its gravitational
Where,
PE
To calculate gravitational PE,
 m = mass (kg)
PE = mgh
 v = velocity/speed (m/s)
Where
 m = mass (kg)
 g = acceleration due to gravity (9.8 m/s2)
 h = height from the ground (m)
Sample Problems
1. A 65-kg rock climber ascends a cliff. What is the climber’s gravitational PE at 35 m above
the base of the cliff?
2. What is the KE of a 44-kg cheetah running at 31 m/s?
Main Form of Energy
1. Mechanical energy
2. Heat energy
3. Chemical energy
4. Electromagnetic
energy
Five Main Forms of Energy
Description
State of
Energy
involves energy from matter
KE
that is in motion
Examples
water in a waterfall,
wind, sound, any
moving object, any
physical activity
any temperature
change, phase changes
(i.e., melting, freezing,
etc.)
involves energy from the
internal motion of
atoms/molecules  the
faster the particles move, the
more heat energy is
produced
involves energy from
forming or breaking bonds
between atoms
KE
PE
jet fuel, gasoline, food,
batteries (all have
stored energy)
involves energy from
moving electric charges
KE
electricity, light, Xrays, radio/TV waves,
laser light
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
5. Nuclear energy
involves energy from the
nucleus (center) of an atom
PE
nuclear fission
(splitting of nuclei)
and nuclear fusion
(joining of nuclei 
powers the sun and
other stars)
The Law of Conservation of Energy states that energy cannot be created or destroyed by
ordinary means; however, it can change from one form to another.
Changes in the form of energy are called energy conversions (or energy transformations.)
One of the most common energy conversions is KE  PE or PE  KE.
 Dropping an book from a table
 Riding a roller coaster
 A pendulum in motion
 Tossing a ball in the air
All forms of energy can be changed to other forms.
Solar powered products (e.g., solar cells)
Sunlight  electricity
Electric motors
Electricity  mechanical energy (movement, sound, etc.)
Robot
Battery  electricity  mechanical energy (movement, sound, etc.)
Photosynthesis
Sunlight  Sugars & starches in green plants (chemical)
Electricity from power plant
Fuel such as coal (chemical energy)/nuclear fission (nuclear energy)
Heated water  steam (heat energy)
Steam turns turbines in generators (mechanical energy)
Generator produced electricity (electromagnetic energy)
Electricity traveled to homes and businesses
Temperature is a measure of the average kinetic energy of all the particles within an object; they
are measured using an instrument called a thermometer. [REMEMBER – KE depends on mass
and velocity. Therefore, the bigger the particles and/or the faster the particles are moving, the
more KE they possess and the greater the temperature.]
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
Temperature Conversions
There are three temperature scales:
o
F = (9/5 x oC) + 32
a) Fahrenheit (oF) – used in weather reports and in cooking
b) Celsius (oC) – commonly used scale in science
C = 5/9(oF – 32)
o
c) Kelvin (K) – SI unit for temperature
K = oC + 273
or
C = K – 273
o
The Kelvin temperature scale contains the lowest/coldest possible temperature – absolute zero (0
K). At absolute zero, the particles of an object have NO KINETIC ENERGY – THE
PARTICLES ARE NOT MOVING! Also, unlike the oC and oF scales, the Kelvin scale has NO
NEGATIVE TEMPERATURES.
Sample Problems
1. Water boils at 100 oC. Express this temperature in oF and K.
2. What is the temperature of absolute zero in oC and oF?
3. The freezing point of water is 32 oF. Convert this temperature to oC and K.
Heat is the transfer of energy from an object with a high temperature to an object with a lower
temperature.
Three methods of heat transfer
1. Radiation – transfer of heat by rays or waves  sun energy reaches Earth this way
2. Conduction – transfer of heat when molecules collide into each other through direct
contact
3. Convection – transfer of heat by the circular flow of a fluid (liquid or gas) due to density
difference
Density describes how light or heavy an object is. Cold air is heavier (more dense) than warm air
because the air molecules are closer together in cooler air. Thus, cold air sinks as warm air
rises. When cold air forces warm air to rise, a circular movement of air, called convection
current, occurs. Similar action will occur with liquids.
-----------------------------------Metals are good conductors, because they can easily carry heat energy. Wood, rubber, and
Styrofoam are insulators, because they are poor conductor of heat.
A physical property, specific heat is the amount of heat energy that will raise the temperature of
1 kg of a substance by 1 K; it describes how much energy is required to raise an object’s
temperature. Some materials can take in more heat than others.
Heat Energy (HE) = cmt
Where
c = specific heat (J/kg K)
m = mass of substance (kg)
t = temperature change = tf – ti (in Kelvin)
NOTE: Heat energy can be gained/absorbed (+) or lost/released (-)
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
1.
2.
Sample Problems
How much heat energy must be transferred to the 420 kg of water in a bathtub in order to
raise the water’s temperature from 25 oC to 37 oC? The specific heat of water at 25 oC is
4186 J/kg K.
What is the specific heat of aluminum with a mass of 0.455 kg that has absorbed 6330 J of
heat energy, thus having a temperature change of 15.5 oC?
Phase Changes – Changes of State of Matter
Absorb Heat Energy
Solid  Liquid
Liquid  Gas
Solid  Gas
Gas  Liquid
Liquid  Solid
Melting
Evaporation
*Sublimation
Condensation
Freezing
Release Heat Energy
An energy change is always the cause for a phase change.
A phase diagram shows the relationship between temperature and heat energy during a phase
change.
Gas
Temperature
Liquid
Solid
Heat energy
During a phase change, the temperature remains unchanged; however, heat energy is absorbed or
released.
 Melting point – the temperature of a substance changing from a solid to a liquid
 Freezing point – the temperature of a substance changing from a liquid to a solid
Note – On the phase diagram, the melting point and the freezing point are the same temperature
 Boiling point – the temperature of a substance changing from a liquid to a gas
 Dew (condensation) point – the temperature of a substance changing from a gas to a
liquid
Note – On the phase diagram, the boiling point and the dew point are the same temperature
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
What are waves?
 Moving disturbances/vibrations that transfers energy (not matter) from one place to
another
 Medium – matter that a wave travels through
 Most waves are mechanical waves (they travels through a medium); electromagnetic
waves do not travel through a medium
 Most waves are periodic; they have a repeating pattern of motion
Two Classes of Waves
Transverse Waves
 These waves moves perpendicular (up-and-down motion) to the direction of the wave
 Water waves and light are examples
Longitudinal (or Compression) Waves
 These waves moves parallel (back and forth) to the direction of the wave
 The “slinky” and sound waves are examples
Characteristics of Waves
A. Transverse Waves
 Crest – the highest point of a wave
 Trough – the lowest point of a wave
 Amplitude – distance of the wave from rest
 Wavelength – the distance from one point of the wave to the same point of the next wave
 Period (T in sec) – the time it takes a wave to pass by a certain point
 Frequency – the number of waves that pass a point in one second [unit of frequency =
Hertz (Hz) = 1/sec] NOTE – Frequency = 1/T (period)
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
B. Longitudinal/Compression Waves
 Compression – areas in medium where particles are squeezed together
 Rarefaction – areas in medium where particles are spread apart
 Wavelength – distance from one compression to the next
 Amplitude – half the distance between compressions
 Frequency – the number of waves per second
||||||||||||| | | | | | ||||||||||||||| | | | | | ||||||||||||||| | | | | | |||||||||||||||| | | | | |||||||||||||||| | | | | | ||||||||||||||||
To calculate the speed of a wave,
Wave Speed () = wavelength () x frequency (f)
 = f
The amplitude of a wave depends on its energy; the larger the amplitude, the greater the energy.
The frequency of wave depends on its speed; the faster the wave is moving, the greater its
frequency. Wavelength and frequency are inversely proportional; waves with shorter
wavelengths have higher frequencies (and vice versa).
The speed of a wave depends on the type of medium it passes through.
Sample Problems
1. What is the speed of a wave that has a wavelength of 1 m and a frequency of 2 Hz?
2. Sound waves travel through air at 343 m/sec. Suppose a sound wave has a frequency of 1000
Hz. What is its wavelength?
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
Waves travel in straight lines until they hit a boundary. When this occurs, one of three things can
happen; the wave will be reflected, refracted, or diffracted.
A. Reflection – the bouncing back
of a wave when it hits a
boundary
B. Refraction – the bending
C. Diffraction – the
of a wave as its changes
scattering of a wave
speed by moving through a
as its hits the edges
different medium
of a boundary or tiny
opening
When two or more waves are moving through a medium at the same time, the energy of the
waves may interact by adding together or canceling out as they pass. This is called interference.
Waves in same medium
Description
Constructive interference
 Crest-crest
overlapping
 Add the amplitudes
 Form bigger wave
Destructive interference
 Crest-trough
overlapping
 Subtract the
amplitudes
 Form smaller wave
(different sizes)
 Form straight line
(same size)
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
General Characteristics of Sound Waves
 Sound waves are longitudinal/compression waves
||||||||||| | | | | ||||||||||| | | | | |||||||||| | | | | |||||||||| | | | |
 direction of wave
 They transfer sound, which is a form of energy, from one place to another
 The sound we hear are produced by vibrations of the longitudinal/compression waves
 Sound waves are mechanical waves – needs a medium
Speed of Sound Waves
 The speed of sound waves depends on the medium which the waves travels and its
temperature
 The closer the particles are in a medium, the greater the speed of sound wave; sound
waves transmit energy faster in substance with smaller spaces between particles more
vibrations
solid (more dense)
liquid
gas (less dense)
speed of sound increase
 Air is the most common medium of sound waves
 The higher the temperature of the medium, the more particles of the medium will
collide (causing vibrations). Therefore, more energy can be transmitted in a shorter
amount of time  increase the speed of sound.
 Sound cannot travel in a vacuum (area where there is no air particles)
Speed of Sound through Various Substances
331 m/sec
3828 m/sec
Air (at 0 oC)
Wood
o
346 m/sec
5103 m/sec
Air (at 25 C)
Iron
o
1454 m/sec
5971 m/sec
Water (at 25 C)
Stone
1. Which of the above items would you believe to be the most dense? Why?
2. What would happen if you increased the temperature of these items?
The speed of sound is much slower than the speed of light (3.0 x 108 m/sec). Light waves travel
through air about one million times faster than sound waves. This is why you see lightning
before hearing the sound (thunder).
Properties of Sound
1. Volume/Intensity – the softness or loudness of sound  depends on the amplitude of the
sound wave
a. The greater the amplitude, the greater the volume/intensity (the louder the
sound)  the more energy a wave has
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
b. SI Unit of volume/intensity – decibels (dB)
10 – 20 dB  very faint
Whisper, human breathing, rustle of
leaves
20 – 40 dB  faint
Quiet home, quite conversation, private
office
40 – 60 dB  moderate
Noisy home, movie theater, loud
conversation
60 – 80 dB  loud
Noisy office, loud radio, opera singers
singing
80 – 100 dB  very loud
Noisy machine shop, rock/rap concert,
truck unmuffled
100 – 120 dB  results in hearing loss
Jet in flight, firing range, explosion
c. Continual/prolonged exposure to sound with an intensity greater than 90 dB can
cause permanent hearing damage/loss
2. Pitch – the highness or lowness of sound  depends on the frequency of the wave
a. The higher the frequency, the higher the pitch
b. The human ear can hear sound frequencies from 20 Hz to 20,000 Hz
c. Sound waves are described as infrasonic (frequencies less than 20 Hz) or
ultrasonic (frequencies greater than 20,000 Hz) most humans cannot hear
either of them
3. Timbre/Sound Quality – the blending of different-frequency sound waves
If the source of the sound wave is moving, like a train blowing the whistle while moving down
the tracks or an ambulance blasting its siren while moving along a street, a phenomenon called
the Doppler effect occurred.
 As the source moving toward the observer, the frequency of the sound wave appears
higher  louder. The sound waves are closer together in front of the source.
 As the source moves away, the frequency of the sound wave appears lower 
softer. The sound waves are farther apart behind the source.
Thus, the Doppler effect is the change in wave frequency (pitch) caused by the motion of the
wave source.
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
In physics, the study of sound is called acoustics. Irregular or unpleasant sounds are
called noise. Too much “noise” may cause health and/or hearing problems. Sounds having a
pleasing quality and a regular pattern are called music.
The reflection of a sound wave is called an echo. If you hear multiple echoes of sounds,
you will experience reverberation – making it difficult to hear clearly. The sounds reflecting off
different things in the room reach your ears at different times. In many auditoriums, theaters, and
concert halls, soundproofing materials (i.e., carpets and long curtains) are placed on walls to
reduce reverberation by absorbing sound and eliminating echoes.
Although human cannot hear them, echoes of ultrasonic waves are useful in many ways.
1. Oceanography – SONAR (acronym for SOund NAvigation and Ranging) use to find the
depth of water or sunken ships.
2. Medicine (called Ultrasound) – use to remove kidney stones and “see” the inside of the
body (locate tumors/gallstones or examine a developing fetus inside their mothers). The
reflected waves are fed into a computer, which provides a picture called a sonogram.
3. Use in cleaning jewelry, machine parts, and electronic components. Items are placed in a
bath of water, and ultrasonic waves are sent  creating strong vibrations in the water the
remove dirt from items in bath.
Electromagnetic (EM) Waves
All EM waves are transverse waves; they moves perpendicular (up and down) to the
direction of the wave
 They can travel in a medium or in a vacuum (empty space with no air particles) – do
not require a medium!
 All EM waves are formed by the motion of electrically charged particles
 All EM waves travel at the same speed in a vacuum: 3 x 108 m/sec (the speed of
light). They travel slower in a medium – still faster than the speed of sound.
 EM waves, however, are classified by their wavelengths and frequencies  SEVEN
TYPES OF EM WAVES
Longest
Lowest
Radio waves

Microwaves
Infrared (heat) waves
Wavelength
Visible light
Ultraviolet (UV) waves
Frequency
(& Energy)
X-rays
Shortest
Gamma rays
Highest
Visible Light and “Seeing” Colors
 The only EM waves the human eye can SEE
 ROY G BIV – the order of colors  increasing frequencies and decreasing
wavelengths
o Red – longest wavelength & lowest frequency
o Violet – shortest wavelength & highest frequency
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE

White light is a mixture of many colors. These colors can be separate when white
light is refracted (bended) in a prism.

Seeing colors
o We can see color because our eyes see each wavelength as a different
color
o When white light strikes most objects, certain colors are reflected
(bounced off) while others are absorbed
o The REFLECTED LIGHT is what you see as color
o [Example] A BLUE object appears blue because it reflects mostly
wavelengths of blue light; all other colors are absorbed by the object
o When all wavelengths/colors are reflected, the object appears white; when
all wavelengths/colors are absorbed, the object appears black
o The human eye can see about 17,000 different colors
Light can be refracted (bended) when it can pass through a different medium.
It can also be refracted when it passes through lens. Light bends toward the thicker part of the
lens.
In convex lens, the light rays converges, or
come together, at a focal point
In concave lens, the light rays diverges, or
spread apart
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
WAVELENGTH
LONGER
SHORTER
RADIO MICROWAVES INFRARED
WAVES
(HEAT)
WAVES
VISIBLE LIGHT
ULTRAVIOLET
XGAMMA
(UV) LIGHT
RAYS
RAYS
R O Y G B I V
LOWER
HIGHER
FREQUENCY AND ENERGY
RED
ORANGE
YELLOW
GREEN
700 nm
BLUE
INDIGO
VIOLET
400 nm
WAVELENGTH ()
TYPES OF
WAVES
RADIO
WAVES
RANGE OF
RANGE OF
USAGES
FREQUENCY WAVELENGTH
Less than
Greater than 30 AM and FM radio; television
1 x 109 Hz
cm
broadcasting; radar; air craft navigation;
MRI in medicine; radio telescopes
1 x 109 –
30 cm – 1mm
Microwave cooking;
MICROWAVES
11
3 x 10 Hz
telecommunication; research on atoms
and molecules
11
3 x 10 –
1 mm – 700 nm Heat radiation from sun; heating lamps
INFRARED
4.3 x 1014 Hz
for warming foods; hair-dryer; heat(HEAT)
sensitive or “night vision” cameras and
WAVES*
weapons
14
4.3 x 10 –
700 nm – 400
Visible light photography; optical
VISIBLE
7.5 x 1014 Hz
nm
microscopes and telescopes
LIGHT
14
7.5 x 10 –
400 nm – 60 nm Sterilizing medical instruments; killing
ULTRAVIOLET
5 x 1015 Hz
harmful bacteria in foods; identifying
(UV) LIGHT*
fluorescent minerals
5 x 1015 –
60 nm – 1 x 10-4 Medical examination of bones, teeth,
X-RAYS*
3 x 1021 Hz
nm
and organs; detected for black holes in
space
18
-5
3 x 10 –
0.1 nm – 1 x 10
Cancer treatment; food irradiation;
GAMMA
3 x 1022 Hz
nm
energy used in nuclear power plants to
RAYS*
create electricity
* Prolonged/excessive exposure to these types of waves can cause serious health problems,
genetic mutation, and even death
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
Electricity is also called electrical energy. It is energy due to the movement of electrically
charged particles.
Two Types of Electricity
A. Static electricity – the accumulation (build-up) of electrically charged particles on an
object  DOES NOT FLOW
a. Take a comb and rub it through your hair; afterwards, use the comb to pick up
small pieces of paper
b. Rub a balloon in your hair and watch as it stick to the wall
c. Walk across a carpeted floor and be stung by a spark when you reach out to touch
something
d. Place clothes in dryer and see how they “cling” to each other
B. Current electricity – the flow of electrically charged particles through a wire or a
conductor (material that can carry electricity through it)
With any type of electricity, it all begins with the atom. In an atom, there are three subatomic
particles:
Particle
Proton
Neutron
Electron
Charge
+1
0 (neutral)
-1
Location
Nucleus
Nucleus
Electron cloud
Movement in Atom
None
None
Constantly in motion
An atom is electrically neutral if it has the same number of protons and electrons. However, in
some atoms, electrons are not held tightly. As a result, those atoms lose electrons  thus,
becoming positively charged. Whereas, in other atoms, they attract additional electrons  thus,
gain electrons and becoming negatively charged.
Static Electricity
Law of Electric Charge: Electrically charged objects obey the following rule: Opposite
charges attract, and like charges repel!
Static electricity can occur in three ways:
By friction
 As two electrically neutral objects are rubbed together, one object will lose electrons
to the other object.
 The object that lost electrons becomes positively charged and the object that gains
electrons becomes negatively charged.
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
By conduction
 When a negatively charged object and a positively charged object are brought
together, the effects of both charges are cancelled out.
 Electrons will move from one (-) object to the other (+) object until both objects are
neutral.
By induction
 A charged object is brought near a neutral object
 The opposite charge will be attracted toward the charged object 
forcing the neutral object to behave as if it was charged
If the charges are strong enough, the objects do not even need to touch for
this exchange to take place. Electrons can jump a gap between two
oppositely charged objects. When this happens, the charge heats the air
enough to make a spark. After the spark (transfer of electrons), both
objects are electrically neutral. This process of transferring electric
charges is called electric discharge. Static electricity may be discharged if
a charged object comes in contact with an object that will accept the
charge. Lightning is a spectacular example of electric discharge.
Current Electricity
The amount of electric current (flow of electrons) depends on the number of electrons passing a
point in a given time. The coulomb (C) is the unit of electrical charge. It takes 6.25 x 1018
electrons to make a charge of -1 coulomb (or 6.25 x 1018 protons to make +1 coulomb).
There are two types of current:
 Direct Current (DC)
o Current that move in ONE direction
o Produced by battery (changes chemical energy into electricity)
 Alternating Current (AC)
o Current repeatedly changing direction (ALTERNATING direction)  travel
longer distances
o Produced by generator (changes mechanical energy into electricity)
Three Basic Units of Electricity
A. Current (I) – flow of electrons [SI Unit – Ampere (Amps or A) = Coulomb/second]
B. Voltage (V) – the work/energy that push electrons from one point to another [SI Unit – Volts
= Joule/coulomb]; also called potential difference
C. Resistance (R) – measures how much a substance opposes the flow of electrons, or current.
(SI Unit – Ohms or ); also called electric friction
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
Ohm’s Law describes the relationship of the three basic units of electricity.
Voltage = Current x Resistance
V = IR
Sample Problems:
1. What is the resistance of a circuit if the current is 4 amps and the voltage is 12 volts?
2. What voltage is needed to cause a current of 3 amps to flow through a 2 ohm resistor?
A circuit is a closed path through which electricity can flow. Every circuit must have these 4
components:
1. A source of electricity – battery (or generator)
a. Will have a positive terminal and a negative terminal
b. Electrons will be “pushed” from the negative terminal at a certain voltage
c. Through a wire, the electrons will flow to the positive terminal
2. A switch
a. Controls the flow of electric current
b. Made of a conductor attached to an insulator (material that cannot carry electricity
through it)
c. When the switch is closed, the current can continue to flow though the entire
circuit; If the switch is opened, NO current can flow
3. One or more loads
a. Provide resistance
b. Convert electricity into other forms of energy, like heat, light or sound
c. Light bulb, toaster, motor, TV, etc. (any electrical device)
4. Wires (at least two)
a. Consist of copper or aluminum (conductor) surrounded by rubber (insulator)
b. Carry electricity between the source and the load(s)
c. Electrons move from the source (- terminal) to the load(s) and back to the source
(+ terminal)
Symbols of Parts of an Electric Circuit
Battery
-
+
Switch
open
closed
Load
any electrical device – zigzag
a light bulb
Wires
or
single
connected
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
Two Types of Circuits
Series Circuit – only ONE path for the current to follow
A break anywhere along the path will stop the current flow
Parallel Circuit – has more than one path for the current to flow
A break along one path will NOT stop the current flow in the other paths
Then there are some circuits that are a combination of series and parallel circuits.
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
Magnetism is a force produced by the motion of charged particles.
A magnetic field is an area around a magnet where the magnetic force
is observed. These lines are a way to show the structure of a magnetic
field. The lines are close together where the magnetic force is strong,
and spread out where it is weak; thus the magnetic force is greatest at
the north and south poles. Also, the line (or “force”) always travels
from the north pole of the magnet to the south pole.
Within a magnet, a group of atoms, called domains, have electrons spinning in the same
directions  creating a magnetic field in the material

Domains lined up in an orderly fashioned  magnetized

Domains in disarray  not magnetized
Every magnet is a dipole; it has two poles – north and south poles. Even if you break a magnet
in half, the two pieces will have their own dipoles.
In fact, our Earth is one large magnet, with its two poles. The north pole of a magnet is attracted
to the magnetic North Pole of the Earth; this explains why, in a compass, the needle always
points north.
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
Think of the Earth as a gigantic bar magnet buried
inside. In order of the compass needle to always
point to the North Pole, we have to assume that the
buried bar magnet has its south end at the North
Pole.
Law of Magnetism states this:
 Like magnetic poles repels
 Unlike magnetic poles attracts
Thus,
N
S
N
S
N
S
N
S
S
N
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
Like any magnet, our Earth has a magnetic field of its own  magnetosphere.

It protects us from solar wind (a stream of
charged particles blown from the sun
which can be harmful to humans)

It creates beautiful auroras
(northern/southern lights) around the
poles, due to charged particles from solar
wind that are trapped in the Earth’s
magnetic field
There are two types of magnets – permanent and temporary.
A. Permanent magnets are substances that are “magnetic” all the time. The most common
permanent magnet is lodestone (or magnetite), a rock mostly made of iron.
B. A temporary magnet (also called an electromagnet) is a device that becomes “magnetic”
when its magnetic field is produced by an electric current.
A simple electromagnet consists of a copper wire wrapped
around an iron nail attached to a battery. To increase its
magnetic strength,
a. Add more coils* (“loops”) around the nail
b. Use iron nails only – no other metal
c. Increase current  use larger batteries
d. Decrease the distance of the coiled iron nail and the
battery
When electricity runs through the wire, it produces a
magnetic field in a specific direction. Use the “right hand
rule” to determine the direction of the magnetic field.
 Your thumb points in the direction of the electric
current

Your fingers point in the direction of the magnetic field
around the wire
*A coil of wire – not wrapped around a nail – used to create a magnetic field is called a solenoid
Just as an electric current can produce a magnetic field around a wire, a magnetic field can also
produced an electric current in a coil of wire. As the coil moves through a magnetic field, it
produces electricity by inducing a voltage from the coil of wire. This is how a generator works.
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
A generator is a machine that changes mechanical energy into (AC) electricity. Below is a
diagram of a simple generator.
NOTE: In the diagram, the coil is stationary and the magnet – providing the magnetic field – is moving. You can
have a coil of wire moving through or around a stationary magnet  found in generators at power plants.
The electricity produced by generators can have its voltage regulated by the use of a
transformer. A typical transformer (shown below) consists of a large iron ring with two coils –
primary and secondary – wrapped around it. AC current flows through the primary coil,
producing a magnetic field in the iron ring that will induce a current in the secondary coil.
We use transformers to change the size of the voltage; we can step the voltage down from a high
voltage to a smaller one or we can step it up.
A. Step-Up Transformers
a. Secondary coil has more loops than the primary coil
b. Outgoing current has higher voltage
c. Used at power plants to transport electricity over longer distances
B. Step-Down Transformers
a. Secondary coil has fewer loops than the primary coil
b. Outgoing current has lower voltage
c. Placed near homes to reduce voltage to safer levels
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GHSGT-SCIENCE_PHYSICS OF PHYSICAL SCIENCE STUDY GUIDE
To calculate the outgoing voltage,
Voltage out = Turns in secondary coil
Voltage in
Turns in primary coil
Sample Problem: The primary coil of a transformer contains 20 turns of copper wire. In the
secondary coil, there are 100 turns of wire. If the voltage going into the transformer is 12 V,
what is the outgoing voltage? What type of transformer is this?
While generators used motion to create
electricity, electric motors used electricity to
create motion. Thus, an electric motor is a
device that changes electricity into mechanical
energy. In a simple electric motor (shown
below), an electromagnet rotates around (or
within) a permanent magnet; this rotation is
due to the magnetic fields alternatively attract
and repel each other.
You know magnets can be used to produced electricity (and vice versa)
Did you know?
Magnets are used in
 Refrigerators, vacuum cleaners, washing machines, CD and DVD players, blenders,
hedge trimmers  any household device that used a motor
 Cars, trains, subways (yes…including MARTA)
 Maglev trains – use repelling forces of magnets to cause the train to levitate (float
above the track); because it levitate, it eliminates friction so these trains can travel at
high speeds
 Computers  information is saved and retrieve
 Audio and video players  used magnetic “heads” to record and read information on
tape covered with tiny magnetic particles
 Speakers and microphones
 Images on TV screen
 Escalators and elevators
 Magnetic Resonance Imaging (MRI) – patient lies between two large magnets,
causing the domains in the human body to align; use to view inside the body
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