Transcript Heat, Force, Motion, Electricity, Magnetism, sound, light

HEAT, FORCE, MOTION, ELECTRICITY,
MAGNETISM, SOUND, LIGHT
Today is the LAST day of Notes!
...As long as you behave tomorrow & Friday!!
Heat & Phase Changes
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What happens to the speed of the
particles in gases as they are exposed to
freezing temperatures?
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They slow down
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What happens if a liquid is vaporized?
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It turns into a gas
Phase Change Graph
Heat
Phase Change Graph
Heat
Phase Change Graph
Heat
Phase Change Graph
Heat
Phase Change Graph
Heat
Phase Change Graph
Heat
Phase Change Graph
Conduction, Convection, Radiation
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This website I’m going to show
you is linked on my
website…www.schoolrack.com/a
browder
Thermal Expansion
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Alcohol & mercury are liquids that are used in
thermometers…why?
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Both expand at predictable rates when heated
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What do you feel as you drive across the James
River Bridge? Why?
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Expansion joints are put on bridges because the
concrete expands & contracts when what
happens?
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The temperature changes
Speed
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At what speed would a bus have to
move in order to travel 40
kilometers in two hours?
What is the formula for speed?
 Speed = Distance ÷ Time
 Speed = 40 km ÷ 2 hr
 20 kilometers/hour
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Work
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What is the definition of work?
• The scientific definition of work = using a force to
move an object a distance
▫ …when both the force and the motion of the
object are in the same direction
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Work requires motion…If there’s no motion, there
is no work being done
Which of the following is work?
A lamp hanging from a ceiling
 A man pushing against a concrete wall
 A car being towed down a street
 A rocket drifting through space
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Which of the following is work?
A lamp hanging from a ceiling
 A man pushing against a concrete wall
 A car being towed down a street
 A rocket drifting through space
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Mechanical Advantage
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A large cart on wheels full of bird seed mix that needs
to be moved onto a moving truck could be moved
either by lifting it above the ground and setting it onto
the truck platform or by using an inclined plane. The
advantage of using the inclined plane is that the work
can be done –
A. more quickly
B. with less friction
C. using less force
D. using less energy
Mechanical Advantage
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A large cart on wheels full of bird seed mix that needs
to be moved onto a moving truck could be moved
either by lifting it above the ground and setting it onto
the truck platform or by using an inclined plane. The
advantage of using the inclined plane is that the work
can be done –
A. more quickly
B. with less friction
C. using less force
D. using less energy
Mechanical Advantage
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A truck manufacturer reduces the mass of a car by
350 kg. If the new design is otherwise identical to
the old design, how will the new truck compare to
the old truck?
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A. It will have a greater gravitational attraction to
the road.
B. It will require more fuel to operate
C. It will need less force to move
D. It will release more gas emissions
Mechanical Advantage

A truck manufacturer reduces the mass of a car by
350 kg. If the new design is otherwise identical to
the old design, how will the new truck compare to
the old car?
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A. It will have a greater gravitational attraction to
the road.
B. It will require more fuel to operate
C. It will need less force to move
D. It will release more gas emissions
Power
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P = w/t
To finish a project 500,000 Joules of work
are needed. The time taken to complete
the project is 50 seconds. How much
power is needed?
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Power = 500,000J ÷50 sec
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10,000 J/sec
Simple Machines
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A wheel & axle is a lever that rotates around a
fixed point. All of the following machines employ
a wheel & axle except a –
A. Bicycle
B. Skateboard
C. Pencil sharpener
D. Crowbar
Simple Machines
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A wheel & axle is a lever that rotates around a
fixed point. All of the following machines employ
a wheel & axle except a –
A. Bicycle
B. Skateboard
C. Pencil sharpener
D. Crowbar
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What type of simple machine is a crowbar?
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Lever!
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Static Electricity
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What are some examples of static electricity?

A balloon sticks to a wall after it is rubbed with a piece of
wool.
Laundry in a clothes dryer sticks together because it becomes
charged with static electricity. The electrons are transferred
as clothes rub against each other in the dryer
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When I comb my hair, the hair appears to be attracted
to my comb. My hair and the comb must have what
type of charges?
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Unlike charges
Current Electricity
Direct Current vs. Alternating Current
 Direct Current = (DC) electric current that
flows through a wire in only one direction
Example = current that flows through
batteries
 Alternating Current = (AC) electric current
that reverses its direction regularly
Example = used to run appliances
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Kinds of Electricity
Static
Current
• An electric charge
that collects or
builds up on the
surface of an
object
• The flow of electric
charges carried
through a material
such as wire or other
conductors
• Examples
– Shocking
– Lightening
• Examples
– Power lines
– Computers
– Appliances
What Is Static
Electricity?
• A stationary electrical
charge that is built up on
the surface of a material
Conductors and
Insulators
Conductors
• Any material
that allows
electric charges
to move through
it
• Examples:
– Metals (esp.
copper)
– Your body
– Electric wires
Insulators
• Materials that
do not allow
electric charges
to flow freely
through them
• Examples:
– Wood
– Glass
– Rubber
Simple Circuits
• Series circuit
– All in a row
– 1 path for electricity
– 1 light goes out and the
circuit is broken and all the
lights go out.
– Shares voltage; current stays
the same across circuit.
– Ex: Old Christmas Lights
• Parallel circuit
– Many paths for electricity
– 1 light goes out and the
others stay on
– Shares current; voltage stays
the same across circuit.
– Ex: Your house, power lines
Series Circuits
Single Path for
Current to Flow
Parallel Circuits
Often missed question…, but you’re
gonna ace it next week!
Correct
answer = F 1
Magnetism
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Magnetism is the
attraction of a magnet
for another object.
A magnetic pole is the
area of a magnet where
the magnetic effect is
strongest.
Electromagnets
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Electromagnets are
strong temporary
magnets.
Magnetism can be
turned on and off
Made by wrapping a
wire around a piece of
iron and sending a
current through the
wire.
Magnetic field is in the
same direction as the
electric current.
Strength of Electromagnets
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There are several ways to
increase the strength of an
electromagnet:
 Increasing the voltage or
current
 Increasing the number of
loops of wire
 Make the loops of wire
tighter
 Increase the number of
nails in the core
 Use iron for the core
Waves
crest
wavelength
amplitude
trough
Identify each of the labeled parts of the wave above.
Identify Compression, Rarefaction, &
Wavelength
A = Nothing
B = Wavelength – the distance between one point on a
compression and the corresponding point on the next
compression in a sound wave
C = Compression – the part that’s squished together
D = Rarefaction – the part that’s spread out
What is Sonar?
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Uses sound waves to measure the
distance between objects underwater
• Sonar
– Sonar is a system of
detecting reflected
sound waves.
– The sonar device
measures the time it
takes to detect the
reflected sound
waves.
Which travels faster, sound or light?
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Light travels faster than sound.
 You see the fireworks before you hear
them
 You see the lightning before you hear the
thunder
Light
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The reason we see things with our
eyes is because light is reflected
Reflection of Light
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Angle of incidence = Angle of
reflection
What property of light causes this
pencil to appear bent?
Refraction – because light travels
slower through water than through air