Download 2 - Mineola ISD

Objective 5 Review
Quick Physics
and Energy
Physics is about
Energy and Motion

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How and why do
things move?
Do planets move the
same way as a ball
that is thrown?
These are the types
of questions physics
tries to answer.
Quick physics
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Speed or Velocity = Distance / Time
Acceleration = Vfinal – Vstart / time to change
Work (joules) = Force (Newton) x distance (meters)
Power (watts) = Work / time
Distance / Time = Speed so
20m / 40s = .5 m/s or . . . .
5

A toy car
moves 20 m in
40 seconds.
What is the
speed of this
car?
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
2
2
2
2
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3
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9
9
9
9
9
9
Acceleration = Vf – Vi / Change in time so . . .
35m/s – 15m/s / 10 s = 2 m/s/s

An object is
moving at 15
m/s and after
10 seconds the
object is
moving at 35
m/s. What is
the acceleration
of the object?
2
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
2
2
2
2
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9

Joe picked up a case of cokes
weighing 50 newtons, 1.5 meters
off the floor. The case contained 12
cans. How much work did Joe do?

a. 0 Joules
b. 6.25 Joules
c. 33.3 Joules
d. 75 Joules
Work = Force x distance
= 50 N x 1.5 m
= 75 Joules
Power = Work/time but nothing here is in Joules
Work = force x distance so . . .
Power = 550N x 5m / 3.5 s = 785.7 watts


a.
b.
c.
d.
Alisha weighs 550 Newtons runs to
the top of the 5 m tall staircase in
3.5 seconds. How much power is
Alisha demonstrating?
385 Watts
559 Watts
786 Watts
9625 Watts
Sir Isaac Newton and the
3 Laws of Motion

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Considered one of the
foremost physicists,
Described the motion of
all things in a gravity
and friction free system.
For each of the next
slides, write at least 3
examples of each law in
action. . .
Newton’s FIRST Law


Law of Inertia
An object at rest or
in motion remains
that way until acted
upon by an
unbalanced force.
Newton’s SECOND Law


If acceleration of a 10 N ball is 20 m/s (sq), what is the acc. of a 5 N ball?
Force = Mass x
Acceleration
The greater the
force on an object
in a single direction
the greater the
acceleration in that
direction will be.
A) 5
B) 10
C)20
D) 40
Newton’s THIRD Law
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Law of Action/Reaction
For every action force
there is an equal and
opposite reaction
force.
Motion is the result of
unbalanced forces on
the same object.
There are 6 simple machines

Lever
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1st Class with the
fulcrum in the middle
2nd Class with the
resistance in the middle
3rd Class with the effort
in the middle
To determine the lever
classes three, what is in
the middle spells FRE.
Pulley, Wheel and Axle,
Inclined Plane, Wedge
and Screw
Mechanical Advantage and
Efficiency, Why Not 100% ?


Mechanical advantage is how
much your force is multiplied
by the machine
Efficiency is

Actual MA/Ideal MA

Never 100% due to
FRICTION

Almost all energy that is
not converted into work
is converted into heat.
Waves

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Transverse Waves

o
vibrate 90 from the
direction of travel.
All electromagnetic
waves are in this group. 
Visible light and the color
spectrum are all
transverse waves.
Water ripple waves and 
microwaves are also of
this type
Compression Waves
move in the same
direction as their
vibration.
Sound waves, caused by
a disturbance, carried
through a medium are of
this type.
Some types of
earthquakes are also
compression waves.
The Electromagnetic Spectrum
Shortest
to
Longest
Gamma
X rays Ultraviolet Visible Infrared Micro- TV/Radio
Radiation
Light
Light Radiaion waves Waves
Remember: Long – Low – Slow: Long wavelength is a low
frequency and slow velocity.

Which of the following waves would
have the highest pitch and lowest
volume?
A
B
C
D
Speed = frequency x wavelength
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All radiant energy
travels at the same
speed.
3 x 108 meters/sec
This is the speed of
light through space.
Radio waves and
nuclear energy
waves travel at the
same velocity.
Speed = frequency x wavelength so
343 m/s = 512.5 Hz x wavelength

a.
b.
c.
d.
A sound wave is traveling at 343
m/s and has a frequency of 512.5
Hz, what is its wavelength?
0.67 m
1.5 m
169.5 m
855.5 m
Light Spectrum
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Visible light is a small part of the
electromagnetic spectrum.
Violet is the shortest
wavelength, red the longest of
visible light.
As wavelength increases,
frequency __________.
Answer: Decreases!
Waves move, so there can be
interference . . .

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When something is an
interference, it changes
the path of movement.
Constructive means it
adds to the wave’s
energy or amplitude
Destructive cancels or
decreases the wave’s
amplitude
The diagram shows waves approaching a barrier.
Which pattern will be formed after the waves
pass through the opening in the barrier?
After passing through the barrier, it
will spread back out and continue on
the same path.
Ohm’s Law
Voltage = Current x Resistance
Standard American Current –
110V @ 15 or 20 Amps
Power, measured in Watts is
P = VI
Voltage = Current x Resistance
9V = Amperes x 6 ohms or 9V/6ohms =

a.
b.
c.
d.
A 9 V battery is connected to a 6
Ohm resistor. How much current
will flow through the circuit?
54 Amperes
15 Amperes
3 Amperes
1.5 Amperes

Which of the following electromagnets would
be able to pick up the greatest number of
paperclips if each one was connected to the
same battery?
A
B
C
D
More current from more wraps means a stronger magnet.
What is the rule for charges and magnetic poles?
LIKE REPELS LIKE! Since the N pole is marked, these
must both be south.
N

a.
b.
c.
In the diagram above, which poles of
the magnets are interacting?
A north and a south pole
Two north poles
Two south poles
Kinetic Energy
KE = ½ m v
2
Ex: A moving car
has the ability to
do work on the light
pole if it hits it.
Gravitational Potential Energy
or Will it fall?
GPE = m g h
m is the mass of the
object in Kg,
g is the acceleration
due to gravity which is
9.8 m/s2 on earth and
h is the height in meters
Use the formula page!
PE = mgh
41 What is the
potential energy
of the rock?
A 59,900 joules
m = 95 kg
B 64,600
g = 9.8joules
m/s2
C 93,100
joules
h = 100
m
D 121,600 joules2
95 kg x 9.8 m/s
x 100 =
93,100 joules C
Law of Conservation of Energy
Energy can change forms,
but is never created nor
destroyed
 Loss in one form = gain in
an another form
 A falling object speeds up
as it falls to the ground; PE
decreases as KE increases.
The KE it has at impact =
the PE it had before it fell.

Example: A falling object
speeds up as it falls to the
ground;
PE decreases as KE
increases, the KE it
has at impact with
the ground is equal
to the PE it had
before it fell
Circuits – 2 types
Series circuits are the
most simple.
 One (1) path for the
current to travel.
 Contains an energy
source, a path, and a
load (something for it
to do, like a lamp)


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Circuits – 2 types
¢Parallel circuits provide more than one
path for the current to travel. ¢Most
circuits are parallel, since if one lamp
goes out, the others can stay lit. ¢
6. Which switches, if opened, will
cause the light bulb to stop
glowing?
F. Q
G.
R
It is the only
H. S
switch in
J. T
series to
both the
battery and
light.
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USE THE FORMULA SHEET!!
¢What is the current in a copper wire
that has a resistance of 2 ohms and is
connected to a 9 volt electrical source?
¢ A. 0.22 amp
¢ B. 4.5 amps
¢ C. 11.0 amps
¢ D. 18.0 amps
V = I R so,
9V = I x 2 ohms or 4.5 amps
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Thermal Energy
¢A body contains internal KE due to the
motion of its atoms ( they are
constantly wiggling and jiggling)
¢Thermal Energy is the total internal KE
of a body
¢Temperature is the average KE of a
body
Heat- Transfer of
Thermal Energy
Three forms of heating:
. Conduction-direct contact,
a pot heating on a stove
(solids)
. Convection- heating by
circulating fluids, (gas and
liquid) heating from a fireplace
nd. . .
1
2
A
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Heat- Transfer of Thermal Energy
1. Conduction-direct contact, a pot
heating on a stove (solids)
2. Convection- heating by circulating
fluids, (gas and liquid) heating from a
fireplace
And. . .
Three forms of heating:
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Heat moves by conduction in solids sinc
e the particles are close together and vi
brate. . .
¢43 Heat convection occurs in gases
and liquids. Heat convection does not
occur in solids because solids are
unable to — ¢A absorb heat by
vibrating
¢B transfer heat by fluid motion
¢C emit radiation by reflecting light
¢D exchange heat by direct contact
Solids do radiate heat to their surroundi
ngs
2 The primary way liquids and
gases transmit heat is by the
process of —
F reflection
G conduction
H radiation
J convection
Fluid heat movement
is convection. Fluid
motion occurs in
liquids and gases.