Objectives
12:
PS.15 The student will infer the nature of heat energy.
I.
Energy
is defined as the capacity to do work ( to move matter from place to place or
to cause matter to change.
a.
Forms
of energy
i.
mechanical
energy- energy of matter in motion.
ii. Chemical energy- stored in
or released from chemical bonds.
iii.
Nuclear
energy- associated with nuclear reactions ( the most concentrated form of
energy)
iv.
Electromagnetic
energy- results from moving electrical charges and light.
v. Heat energy- caused by the
internal motion of atoms.
vi.
Law
of conservation of energy- energy is neither created nor destroyed only
converted
b. Measuring energy
i.
types
of energy
1. Potential energy- stored
energy due to chemical bonds or gravity
2. Kinetic energy-Energy due to
the motion of an object
ii. Temperature-is the measure
of the internal kinetic energy
1. Celcius- 0 degrees freezing
for water and 100 degrees for boiling point
2. Kelvin- based on absolute no
motion of particles
a.
has
a temperature the measures no motion -absolute zero
b. Kelvin = 273 + celsius
c.
Moving
heat energy
i.
Conduction-
moving heat due to collisions of particles
1. conductors- allows heat to
move
2. insulators- stops heat from
moving
ii. Convection- movement of heat
due to fluid movement
iii.
Radiation-
moves through space by electromagnetic waves.
PS. 16 The student will demonstrate the implications of energy conservation
a.
The
total amount of energy is constant and can be only converted
b. How can we manage energy?
i.
use
more efficient transportation
ii. reducing energy loss in
heating and cooling
iii.
turning
off electric appliances when not needed
iv.
Recycling
PS. 17 The student will describe the concept of force
a.
Force
is defined as a push or a pull exerted on matter.
b. SI unit of a Newton (N) = 1kg m/s2
c.
Newton’s
Three Laws of Motion
1. First Law of Motion- Law
of Inertia- an objects motion remains
constant.
i.
the
object keeps moving
ii.
keeps
sitting still
iii.
keeps
moving in a straight line
iv.
Inertia-
is matter’s resistance to change in motion
2.
Second
Law of Motion- Law of acceleration-
when a net force causes an object to accelerate.
i.
mass
is inversely proportional to acceleration when the force is constant
ii.
F=
m X a
iii.
Practice
3.
Third
Law of Motion- Law of action-reaction- for every action there is an equal and
opposite reaction.
d. Types of Forces
1. Friction- contact forces
2. Gravitational- due to mass
of objects
3. Magnetic attraction and
repulsion-due to magnetic forces
4. Electrical attractions and
repulsion-due to movement of electrons
IV.
Objective 15.
PS. 18 The student will analyze the concept of work.
a.
Work-
is defined as a force in the same direction as the motion of the object.
b. Work = Force x Distance
c.
SI
unit is Joule (J)= 1 Newton meter
d. Practice problems
PS. 19 The student will explain how machines enable us to do work.
a.
Machine
is a device that makes work easier.
b. Three ways to make work
easier
1. decreasing the input force
2. increasing the output force
3. chaining the direction of
input force
c.
Mechanical
Advantage (MA) – tells the difference in the input and output forces
1. input force- is what you do
2. output force – is what the
machine does
3. MA = resistance force /
effort force
4. MA= Effort distance /
resistance distance
d. Work input
1. the work done by the person
2. includes the work due to
friction
e.
Work
output
1. is always less than WORK
INPUT
f.
Efficiency-
tells how good a machine works
1. Never more than 100%
2. Efficiency = (Work output /
work input) X 100%
g.
6
Types of machines
1. Incline plane- ramp
2. Lever- a bar that pivots
around a fixed point.
a.
first
class- E F R
b. Second class – E R F
c.
Third
class- F E R
3. Screw- a incline plane
wrapped around a singe point
4. Wedge-a moveable incline
plane
5. Wheel and Axle- consist of a
one larger and one smaller circle.
a. MA= large radius divided by small radius
6. Pulley-a rope or chain that
moves on a wheel.
a.
MA=
count the number of ropes
PS. 20 The student will describe the concept of gravity
a.
Gravity-
the force of attraction that exist between all objects.
b. The force of gravity depends
on two things.
1. mass
2. distance
PS. 21 The student will analyze linear motion.
a.
Kinetic
molecular theory- the theory that all matter is in constant random motion.
b. Linear motion- is a change
in the speed or direction of the constant random motion.
1. Speed- describes how fast an
object moves
a.
speed-
distance / time
b. SI units m/s
2. Velocity- describe the speed
and direction of an object
a.
Velocity
= distance / time
b. Units must include
direction Ex. 55 m/s east
3. Acceleration- a change in
velocity or direction
a.
Acceleration
= change in velocity / time
b. Change in velocity = final
velocity – initial velocity
c.
SI
units m/s2 .
d. Gravity is a force that
causes objects to accelerate
4. Terminal Velocity- the
maximum velocity an object can reach
5. Momentum – depends on the
mass and the speed of an object in motion
a.
Momentum
= mass x velocity
b. Law of conservation of
momentum- momentum is neither created nor destroyed.
c.
Elastic
collisions- a collision which there is no transfer of momentum to heat or
friction.
PS. 23 The student will demonstrate how waves interact with matter.
A.
Waves
provide a means of transferring energy from one place to another.
1. Waves carry energy but not
matter
2. Waves travel through a
medium- what carries the wave.
B.
2
Types of waves
1. Longitudinal wave- the
medium moves in the same direction as the wave.
a.
parts
of a wave
I.
Compression-
areas where the medium is are squeezed together
II. Rarefaction- areas in medium
where particles are spread apart
III.
Amplitude-
half of the distance between compressions
IV.
Wavelength-distance
between one compression to the next
V.
Frequency-
the number of waves per second
2. Transverse wave- the medium
moves at right angles to the direction of the wave.
a.
parts
of a wave
I.
Crest-
the highest point of the wave
II. Trough- the lowest point on
the wave
III.
Amplitude-
distance of a wave from rest
IV.
Wavelength-
the distance from one point on a wave to the same point on the next wave.
V.
Frequency-The
number of waves that pass a point in one second. The unit of frequency is the
Hertz, Hz
b. Wave speed
I.
wave
speed = frequency x wavelength
II. as frequency increases then
the wavelength decreases
C.
What
can waves do?
1. Reflection- the bouncing of
a wave when it strikes a barrier.( mirrors)
I.
Angle
of incident- the angle between the incoming wave and the normal.
II. Angle of reflection- the
angle between the outgoing wave and the normal.
III.
Law
of reflection = the angle of incident = the angle of reflection.
2. Refraction- the bending of a
wave as it passes through a medium ( lenses)
3. Diffraction- the scatting of
a wave as it passes an edge.
4. Interference- when two or
more waves passe through a given medium at the same time.
I.
Constructive-
the increase of amplitude of a wave
II. Destructive- the decrease of
amplitude of a wave
PS. 24 The student will analyze electromagnetic waves.
A.
Electromagnetic
waves- are transverse waves created by transverse and magnetic fields
1. travel at constant speed
2. C = 3.0 X108 m/s
3. Light is one form of
electromagnetic waves
a.
light
waves is made up of tiny bundles of light called photons
b. Visible light is made up of
seven colors
1. ROYGBIV
2. Red, orange, yellow, green,
blue, indigo, violet
B.
Types
of Electromagnetic waves
1. Radio waves- lowest
frequency
2. Infrared waves- heat waves
3. Visible light- light that
can be seen by the naked eye
4. Ultraviolet rays- higher
energy and can damage cells
5. X-rays- can pass through the
soft tissues of the body.
6. Gamma rays- have the highest
frequency and shortest wavelength.
C.
two
ways light acts
1. Luminous- objects that
produce light
2. Illuminated- objects that
reflect light
D.
Light
and lenses
1. Concave- spreads light out
2. Convex- produces a focal
point.
3. Prisms- spread light
producing the visible light spectrum
PS. 25 The student will describe the nature of sound.
A.
Sound-
is a longitudinal wave produced by vibrations
B.
Speed
of sound
|
Medium |
Speed
(m/s) |
|
Air |
331 |
|
Water |
1498 |
|
Wood |
3850 |
|
Glass |
4540 |
|
Steel |
5200 |
|
Granite |
6000 |
C.
Amplitude
is measured in decibles (dB)
D.
Frequency
relates to pitch- frequencies higher than 20,000 Hz are called Ultrasound
E.Noise- irregular or unpleasant sounds / music-
pleasing sound
F. Resonate- amplifying certain
frequencies
G.
Echo-
reflecting sound / reverberations
multiple echos
PS. 27 The student will describe various methods of generating electricity
A.
Electricity-
is due to the movement of electrons
1. charged particles are
Protons (+) and Electrons (-)
2. Law of electric charge
states that like charges will repel and unlike charges will attract.
B.
Types
of electricity
1. Static electricity- a build
up of charge that is not moving
a.
Caused
by
1. Friction
2. Conduction
3. Induction
b. a discharge of static electricity cause a spark
2. Current electricity- a
movement of a charge
a. grounding- a safety feature
b.
Caused by 5 ways
1. Electromagnetic generators
2. Electromagnetic batteries
3. Solar Cells
4. Thermocouples
5. Piezoelectric crystals
c.
Types
of current-
1. Alternating current-
produced in power plants and used in homes
2. Direct current- produced by
battery’s use of chemical potential energy.
3. Thermocouples- produced from
a difference in temperature
4. Solar cells- produced
through the photoelectric effect
5. Piezoelectric cells-
produced by applying pressure to a crystal.
PS. 28 The student will differentiate between an
insulator and a conductor.
A.
Conductors-
materials that allow electrons to pass
1. These materials are usually
good electrical and heat conductors
2. Best conductors are metals-
silver, copper, aluminum
3. Superconductors- are
materials that have extremely low resistance at certain temperatures.
B.
Insulators-
are materials that do not allow electrons to pass through.
1. Plastics, rubber, glass,
wood, air
PS. 29 The student will describe electrical circuits and demonstrate safe uses of electrical devices.
A.
Electrical
circuit- is a pathway for an electrical current
1. Two types of circuits
a.
Series-
only one path
b. Parallel- alternate paths
for electricity
2. Short circuit- when a
circuit has low resistance, which increases current flow to dangerous levels.
3. Safety tools
a.
fuse-
contains a metal strip that melts
b. Circuit breakers- contains a
bimetallic switch that can be reused.
c.
Ground-fault
interrupter (GFI)- cuts off outlets when a slight change in current occurs.
PS.30 The student will discriminate relationships among units in electrical circuits.
A.
coulomb
( C ) – is the unit of electrical charge.
B.
Ampere
( amp) – is the rate of current flow
C.
Voltage
( V) – is the potential difference or difference in charges
D.
Ohms
Law- resistance = voltage/ current or R = V/I
E.Watt ( W ) - a measure of electrical power a 1000 W = Kilowatts
F. Power = voltage x current or P = VI
PS. 31 The student will analyze the relationship between an electric current and its magnetic field.
A.
Magnetism-
is a force produced by the motion of charged particles.
B.
Magnetic
field- is the area around an objects that is affected by the magnetic force.
C.
Magnets
are created by electrons spinning in the same direction – domains
D.
Poles-
north and south
1. aurora borealis- northern
lights
2. Aurora australis- similar
effect in at the south pole.
E.Law of Magnetism- states that like repels and
opposites attract.
F. Electromagnetic- a magnet
created by the movement of electricity
G.
Transformer-
uses the design of a electromagnetic to reduce voltage
1. Primary coil- has more loops
2. Secondary Coil-has fewer
loops
3. The ratio of loops
determines the voltage step down.