Transcript Period 2 - Science 6

Final Review!!
Do Now:
Review Today
We will play bingo at
the end to practice
the vocabulary.
The practical will count for 25% of your Final
Your Final counts for 8% of your overall grade
The practical – This Thursday in class!!
th
Location for June 19 Exam
Period 1 – room 210 (Mr. Plaice)
Period 2 – room 211 (Mrs. Webb)
Period 6 – room 212 (Mr. Tolve)
Period 7 – room 209 (Ms. Tamalonis)
Bring 3 pencils & your brain!
(no pens, no calculators)!
Arrive by 8:15 am!
Exam starts at 8:30 am and
you must stay until 10 am!
Work output can never be greater than work
input. Machines do not save work, they make
work easier.
Remember W= F x d so if we increase force, we
must decrease distance and if we decrease force,
we must increase distance
When machines make work
easier we call it mechanical
advantage.
Mechanical advantage:
number of times a machine increases the force exerted on it
MA = output force
Input force
When the output force is greater than the input force, the
mechanical advantage is greater than 1!
Example: If you exert a force of 5 N on a hand-held can
opener, and the opener exerts a 20 N force on the can the
mechanical advantage can be calculated
Mechanical advantage = 20 N = 4
5N
Efficiency is how much work you get out compared to the
amount of work you put into a machine. Mechanical
efficiency is always less than 100% because of friction.
A machine with 100% efficiency would be called an
ideal machine. When we talk about mechanical advantage,
we will be talking about MA in an ideal machine.
X 100%
Brain Pop: Hybrid Cars
The more moving parts a
machine has, the lower its mechanical
efficiency, because of friction.
Ideal mechanical advantage (IMA): Does not take friction
into consideration!
IMA = Distance from the fulcrum to the input force
Distance from the fulcrum to the output force
• If the fulcrum is in the middle of the bar, IMA is 1.
• If the fulcrum is closer to the output force, the IMA is
greater than 1.
• If the fulcrum is closer to the input force, the IMA is less
than 1, but the distance is increased.
MA Video Clip
What is energy?
Energy is the ability to do work
The more energy something has, the more work it can do.
Remember…
Work = Force x Distance
or
w=f x d
Video Clip
Potential and Kinetic Energy
Kinetic Energy: Energy of Motion
Potential Energy: Energy of Position
Kinetic Energy Calculations
Kinetic Energy = ½ mass x velocity2
KE= ½ m x v2 or KE = m x v2
2
Units: Joules (1 J = 1 N•m)
Example: What is the kinetic energy of a 24 kg ball
that is moving with a velocity of 2 m/s?
KE= m x v2
2
KE= 24 kg x (2 m/s) 2
2
KE= 48 Joules
Potential Energy Calculations
Potential Energy= weight x height
PE= weight x height
Units: Joules
But…how do we calculate weight?!?!?!
Weight= mass x acceleration of gravity (9.8 m/s2)
weight= m x agravity
agravity=9.8 m/s2 ALWAYS!!
Units: kg-m or Newtons
s2
Conservation of Energy
The law of conservation of energy
states that energy can not be created
or destroyed.
The big picture… the total energy
in the universe remains constant.
FORMS of ENERGY
1.Mechanical
2.Heat
3.Chemical
4.Electromagnetic
5.Nuclear
6.Light
7.Sound
Energy Transformations:
Most forms of energy can
be transformed into other
forms.
A change from one
energy form into another
is called energy
transformation.
1) Single energy transformation:
one form of energy is changed into
another in order for work to be done.
(Examples: cell phone transforms
electrical energy into electromagnetic
energy. Your body transforms chemical
energy (food) into mechanical energy)
2) Multiple Transformations: when one
form of energy is transformed
into a
series of other forms of
energy
(Examples: mechanical
energy used
to strike a match is transformed into
thermal energy
and light)
Where do we get energy? Mostly from the sun.
Just about all the energy we use comes from the sun and is collected
somehow and then we use it. The sun's energy is collected by plants,
which may turn into fossil fuels, or an ear of corn. The sun's energy is
collected by water that may evaporate and then fall as rainfall above
a hydroelectric dam. The sun's energy is collected by the air, which
causes it to bunch up in some places and spread out in others. The air
then responds by moving from one place to another, perhaps past a
windmill.
What are our sources of energy?
•Oil
•Biomass
•Coal
•Wind
•Solar
•Nuclear
•Nonrenewable
•Moving
water [hydro-]
•Fossil Fuel
•Natural Gas
•Geothermal
•Renewable
Renewable or NON-Renewable?
• Renewable: The source of energy constantly
regenerates itself.
• NON-renewable: Once the energy is
consumed it is gone. It is not replaced.
Brain Pop: Energy
Temperature is a measure
of how “hot” or “cold”
something is.
Temperature is
measured in arbitrary
units, like Fahrenheit,
Celsius or Kelvin.
Heat is the thermal energy
transferred from a hot
object to a cold object.
Heat is measured
in energy units -Joules or
calories.
Latent Heat
The heat absorbed or released by a system during
a phase change at constant temperature.
Video Clip
Heat Transfer
Heat (thermal energy) moves from a hotter to a cooler objects
a) Conduction- heat transfers when solids touch (touching hot spoon)
b) Convection- particles in gases and liquids move in a circular
pattern (boiling water, hot air rising & cool air sinking)
c) Radiation- heat moves out in all directions (the sun, a fire)
Video Clip
Conductors and Insulators
• Conductors — Materials that allow heat to quickly
pass throughout the material (such as metals).
• Insulators — Materials that do not allow heat to
quickly pass throughout a material (such as wood
or plastic).
– This mainly deals with the movement of electrons.
– Metals have a “sea of electrons” that allows for quick
heat transfer.
MAGNETISM
Brain Pop: Magnets
Invisible force of “push” or “pull” by an object.
Wagon does not move;
forces are not lined up
Hi! We’re e- (electrons)!!!
We usually speed around the
outside of the nucleus
In these atoms, each e- is
going its own way
Wagon moves;
forces are lined up
But in a magnet or a metal, we can
line up to become magnetic
Lined up atoms/
electrons=Domain
Magnet Properties
1. Domain (lined up atoms)
2. Polarity:
-
Like Poles repel one another
-
Opposite poles attract to one another
3. Must have more than one pole
*** magnetic poles cannot be isolated***
Mechanical Waves
• REQUIRE a medium for the energy to travel
from particle to particle
Examples: water waves, sound waves, energy
moving through a slinky.
Wave Properties
• Amplitude
• Wavelength
• Frequency
• Amplitude (wave height) – loudness
• Frequency (wavelength) – pitch
Sound
Brain Pop
• Sound is a mechanical wave (requires a
medium to travel) and a compressional wave
(molecules colliding)
• The medium sound travels through are
molecules when they collide
• Sound cannot travel
through the vacuum
of outer space
(no air to travel through)
Sound
Sound
Song
Video
Clip
• Sound is produced when an object vibrates.
• When an object vibrates it exerts a force on
the surrounding air
• Loudness of a sound is recorded in decibels
• As a sound gets louder, the amplitude of the wave
increases
The Doppler Effect:
an increase (or decrease)
in the frequency of sound,
light, or other waves as
the source and observer
move toward (or away
from) each other. The
effect causes the sudden
change in pitch noticeable
in a passing siren, as well
as the redshift seen by
astronomers.
Video Clip
Electromagnetic Waves
• Waves that DO NOT require a medium for the
energy to travel
• Examples: Light, radio waves, x-rays, gamma
rays, etc. All waves on the electromagnetic
spectrum
In a vacuum
light travels
300,000,000 m/s
ROYGBIV Song
Electromagnetic Waves (cont.)
• Radio – listen to your
favorite station
• Microwaves – heat food
• Infrared – night vision
• Visible – you can see this
presentation
• Ultraviolet – tanning
• X-ray – see broken bones
• Gamma – kill cancerous
cells (very dangerous)
Light
• Electromagnetic wave that travels transversely
(up and down motion) as radiation
• White light is made up of all colors
• Black is the absence of color
Brain Pop
Light:
1) Travels in a straight line
2) When hitting a surface,
light is reflected
3) Light can be refracted –
when light travels through a different material it can change
speed (this causes it to look like it bends)
Example: When light goes through water it slows down, when
light goes through a prism we get ROYGBV
Forming Images
When light hits a flat
surface (like a mirror) it
is reflected.
Flat mirrors- you to see a
virtual image- an image
that only seems to be
where it is. Your image
appears to be the same
distance behind the
mirror as your are in
front of the mirror.
• Objects that do not let
light pass through them
are opaque. Ex. Walls,
your desk
• Objects that let light pass
clearly through them are
transparent. Ex.
Windows, plastic wrap,
eye glass lenses
• Objects that let only some
light pass through are
translucent. Ex. waxed
paper, frosted glass
Let’s Play Bingo!!
Pick from the following words to label
each box on your BINGO board.
Write out the words in random order!
Fulcrum
Mechanical Advantage
Efficiency
Ideal Machine
Kinetic Energy
Potential Energy
Renewable
Non-renewable
Temperature
Latent Heat
Conduction
Convection
Radiation
Conductor
Insulator
Magnetism
Domain
Polarity
Mechanical wave
Electromagnetic wave
Loudness
Pitch
Decibels
Doppler Effect
Ultraviolet
Visible light
Refraction
Reflection
Transparent
Opaque
Translucent
Infrared
Gamma Rays