Physics – End of Third Trimester Exam Review (Chapters 12 & 25 – 28)
Chapter 12 – Universal Gravitation
(For Study and Review visit: PHSchool.com Web Code: csd-1120)
Concepts:
The moon and other objects in orbit around Earth are actually falling toward Earth, but have
enough tangential velocity to avoid hitting Earth.
According to Newton’s Law of Universal Gravitation, everything pulls on everything else with a
force that depends upon the masses of the objects and the distances between their centers of
mass.
o The greater the masses, the greater the force is.
o The greater the distance, the smaller the force is.
Gravitation decreases according to the inverse-square law. The force of gravity weakens as the
distance is squared.
Terms To Know:
Inverse-Square Law
Law of Universal Gravitation
Perturbation
Universal Gravitational Constant (G)
Chapter 25 – Vibrations and Waves
(For Study and Review visit: PHSchool.com Web Code: csd-4250)
Concepts:
A vibration is a wiggle in time, and a wave is a wiggle in time and space.

The period of a wave is the time it takes for one complete back-and-forth vibration.

The wavelength is the distance between successive identical parts of the wave.

A wave carries energy from a vibrating source to a receiver without transferring matter
from one to the other.

The wavelength multiplied by the frequency, or the number of bibrations in a given time,
equals the speed of the wave.
In a transverse wave, the medium moves at right angles to the direction in which the wave
travels.

Electromagnetic waves, such as light and radio waves, are transverse.
Physics – End of Third Trimester Exam Review (Chapters 12 & 25 – 28)
In a longitudinal wave, the medium moves back and forth parallel to the direction in which the
wave travels.

Sound waves are longitudinal.
Interference patterns occur when waves from different sources arrive at the same point at the
same time.

In constructive interference, crest overlaps crest, or trough overlaps trough.

In destructive interference, a crest overlaps a trough.

In a standing wave, points of complete destructive interference (at which the medium
does not move) remain at the same location.
The Doppler Effect is an observed shift in frequency received due to the motion of a vibrating
source toward or away from a receiver.
Terms to Know:
Amplitude
Antinodes
Blue Shift
Constructive Interference
Crest
Destructive Interference
Doppler Effect
Frequency
Hertz
In Phase
Interference Pattern
Longitudinal Wave
Node
Out of Phase
Period
Red Shift
Sine Curve
Standing Wave
Transverse Wave
Trough
Vibration
Wave
Wavelength
Chapter 26 – Sound
(For Study and Review visit: PHSchool.com Web Code: csd-4260)
Concepts:
Sound waves are produced by the vibrations of material objects

A disturbance in the form of a longitudinal wave travels away from the vibrating source.

High-pitched sounds are produced by sources vibrating at high frequency, while lowpitched sounds are produced by low-frequency sources.
Physics – End of Third Trimester Exam Review (Chapters 12 & 25 – 28)
Sound waves consist of traveling pulses of high-pressure zones, or compressions, alternating
with pulses of low-pressure zones, or rarefactions.

Sound can travel through gases, liquids, and solids, but not through a vacuum.

Sound travels fastest through very elastic materials, such as steel.
Every object vibrates at its own set of natural frequencies

When an object such as a sounding board is forced to vibrate by a sound source, the
sound becomes louder.

When an object is forced to vibrate at one of its own natural frequencies, resonance
occurs and the sound becomes much louder.
Like any waves, two sound waves can exhibit interference and make sound louder or softer.

Rapid changes in loudness, known as beats, occur when two tones very close in
frequency are heard at the same time.
Terms to Know:
Beats
Compression
Forced Vibration
Infrasonic
Natural Frequency
Pitch
Rarefaction
Resonance
Ultrasonic
Chapter 27 – Light
(For Study and Review visit: PHSchool.com Web Code: csd-4270)
Concepts:
Light has a speed of 300,000,000 m/s in a vacuum, and lower average speeds in matter
Light is energy that travels in electromagnetic waves within a certain range of frequencies.

Light is produced by vibrating electric charges in atoms.

Light passes through materials whose atoms absorb the energy and immediately reemit it
as light.

Light doesn’t pass through material when the energy is changed to random kinetic energy
of the atoms.
Physics – End of Third Trimester Exam Review (Chapters 12 & 25 – 28)
Light waves are transverse, so they can be polarized (with vibrations all in the same direction).

Polarizing filters transmit components of incident non-polarized light that are parallel to
the polarization axis, and block components vibrating at right angles to the polarization
axis. The result is the emergence of polarized light.
Terms to Know:
Electromagnetic Spectrum
Electromagnetic Wave
Infrared
Light-Year
Opaque
Photon
Polarization
Ray
Transparent
Ultraviolet
Chapter 28 – Color
(For Study and Review visit: PHSchool.com Web Code: csd-4280)
Concepts:
White light is a combination of light of all visible frequencies.

Black is the absence of light; objects that appear black absorb all visible frequencies.
The color of an object is due to the color of the light it reflects (if opaque) or transmits (if
transparent).

Light is absorbed when its frequency matches a natural vibration frequency of electrons
in the material illuminated by the light.
Color mixing by addition is the mixing of light of different frequencies.

The eye sees a combination of red, green, and blue light of equal brightness as white.

Red, green, and blue are the additive primary colors.
Color mixing by subtraction is the mixing of colored paints of dyes, which absorb most
frequencies except for the ones that give them their characteristic color.

When paints or dyes are mixed, the mixture absorbs all the frequencies each paint or dye
absorbs.

Magenta, cyan, and yellow are the subtractive primary colors.
Physics – End of Third Trimester Exam Review (Chapters 12 & 25 – 28)
Scattering of violet and blue frequencies of sunlight in all directions is what gives the sky its blue
color.

When sunlight travels a long path through the atmosphere, as at dawn or sunset, only the
lower frequencies of light are transmitted; the higher ones are scattered out.
Atoms of each element have characteristic line spectra that can be used to identify the element.
Terms to Know:
Additive Primary Colors
Complementary Colors
Line Spectrum
Pigment
Scatter
Spectroscope
Spectrum
Subtractive Primary Colors
White Light