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Science on Vacation!
3rd/6th Grade
Greenbriar West Elementary
By Darren McKnight
Fall 2004
Topics
• Flying to Colorado
• Driving to Colorado Springs
• Going to the Top of Pikes Peak
• Going to the Pool
Teaching Strategy
• Lecture
– Reinforce terms from handout provided by GBW
– Interactive – use handout as framework, not many answers
on the sheets
–
marks the sheets the students will get
• Lab
– Provide handout for lab groups to use
– Draw the “approved solution” on the board after the lab
• Test/Quiz
– Review concepts from lecture and observations from the lab
What is Science?
• Science is the methods by which people try to
explain what happens around them
– Why does an apple fall down rather than up?
– Why do winds blow?
– Why doesn’t a swing swing forever?
• Follows the “scientific process”
– Observations: note physical activity
– Hypothesize: propose an “if-then” explanation
– Experiment: organized way to prove or disprove
hypothesis by taking data
– Conclusions: make summary statement or equation to
represent how nature behaves
Flying to Colorado
Greenbriar West Elementary
By Darren McKnight
Fall 2004
Mass – Key Points
• What is mass?
• Does a party balloon have more mass than a
candy bar?
• How do you figure out an object’s mass?
Mass – Key Points Answers
• What is mass?
– Matter or stuff
• Does a party balloon have more mass than a candy
bar?
– Bring in one of each; contrast size vs mass – it
depends but probably not
• How do you figure out an object’s mass?
– Weigh it; but is mass the same thing as weight? No,
will talk about this in a moment; mass of something is
the same no matter what but its weight varies…
Mass and Inertia
• “Inertia is the measure of resistance to change
in motion…”
– What makes something hard to move? _________
• “Unless acted upon by an outside force, an
object remains at rest or an object in motion
stays in motion.”
– What is an “outside force” that often causes
moving objects to slow down? ______________
Mass and Inertia
• “Inertia is the measure of resistance to change in
motion…”
– What makes something hard to move?
• If it is heavier – has more mass
• “Unless acted upon by an outside force, an object
remains at rest or an object in motion stays in
motion.”
– What is an “outside force” that often causes moving objects
to slow down?
• Friction
Force – Key Points
• What is a force?
• Why does gravity exert a force on you?
• If an object is not moving does that mean
that there are no forces on it?
Force – Key Points Answers
• What is a force?
– Something that pushes or pulls you
• Why does gravity exert a force on you?
– Two objects with mass attract each other, so the Earth
pulls the objects towards it
• If an object is not moving does that mean that
there are no forces on it?
– It may but it probably means that the forces acting on
an object cancel out
Forces
The man is standing still.
Are there any forces
on the man?
If so, draw them.
floor
Forces
The force due to gravity
is the same in size,
but opposite in
direction, to the force
by the floor!!!!
Gravity
Floor
Gravitational Force - Questions
• So what causes a gravitational force?
Gravitational Force - Answer
• So what causes a
gravitational force?
– Two objects are attracted to
each other
Object 1 (has mass)
F1
F1 = F2
•Gravitational force
keeps us “stuck” to the
Earth!!!
•We actually pull on the
Earth but the Earth is too
big to move!!!
F2
Person
F
Object 2 (has mass)
Fperson = Fearth
F
Earth
Universal Law of Gravitation
• F = m (GMe/Re2) = mg
– Where
•
•
•
•
•
F = force on an object with mass, m
G = gravitational constant = 6.7 x 10-11 m3/kg*s2
Me = mass of the Earth = 5.94 x 1024 kg
Re = radius of Earth = 6.38 x 106 m
g = acceleration due to gravity = 9.81 m/s2
• Circle the terms above that are constants
Universal Law of Gravitation
• F = m (GMe/Re2) = mg
– Where
•
•
•
•
•
F = force on an object with mass, m
G = gravitational constant = 6.7 x 10-11 m3/kg*s2
Me = mass of the Earth = 5.94 x 1024 kg
Re = radius of Earth = 6.38 x 106 m
g = acceleration due to gravity = 9.81 m/s2
• Circle the terms above that are constants
– But note that G is the only true constant because if
you go to another planet the other terms will vary…
Gravitational Force - Questions
• Is there a gravitational force on a person
standing on the moon?
– Is it larger or smaller than the gravitational
force on the Earth?
– Why?
Gravitational Force Answers
• Is there a gravitational force on the moon?
– Is it larger or smaller than the gravitational
force on the Earth?
• The gravitational force is smaller on the moon.
– Why?
• The moon is smaller (less massive) than the Earth.
• It is actually 1/6 the mass so someone’s weight on
the Moon would be 1/6 of what it would be on Earth
– A 90 lb student would weigh only 15 lbs!!!!!!
Acceleration Due to Gravity
• Due to the force exerted as a result of the
mass of the Earth an object is accelerated
(I.e. the speed increases) when released
At time = 0 seconds, an object is released with no velocity
One second later, it is going 9.81 m/s
Therefore, the acceleration due to gravity is 9.81 m/s per second
which is the same as 9.81 m/s2
Science Terms
• Constant – item that does not change
• Variables – things in an experiment that change
• Independent Variable – variable that is changed
• Dependent Variable – variable that is measured (it
“depends” on the other settings)
Weight vs Mass
• Weight is a force: W = m g
PLOT THE DATA!!
m (kg)
W (N)
10
98
5
49
12
118
5
52
18
177
5
47
8
78
Weight, N
– m = mass and
– g = acceleration due to gravity = 9.81 m/s2
180
160
140
120
100
80
60
40
20
0
0 2 4 6 8 10 12 14 16 18 20
Mass, kg
m (kg)
W (N)
10
98
5
49
12
118
5
52
18
177
5
47
8
78
Weight, N
Weight vs Mass
180
160
140
120
100
80
60
40
20
0
X
X
X
X
X
X
X
0 2 4 6 8 10 12 14 16 18 20
Mass, kg
Weight vs Mass Experiment
• What observations can you make?
• What is the constant?
• What is the independent variable?
• What is the dependent variable?
Weight vs Mass Experiment
• What observations can you make?
– If the mass goes up then weight goes up, plot is a line
(I.e. linear relationship)
– Highlight that this is a hypothesis!!!!!
• What is the constant?
– Acceleration due to gravity
• What is the independent variable?
– Mass in kilograms
• What is the dependent variable?
– Weight in newtons
Why does an airplane fly?
• This is a review of force concepts
What are the four forces
on an aircraft and where
do they come from?
Why does an airplane fly?
• This is a review of force concepts
Lift – caused by flow over wings
Drag – caused by aircraft
surfaces rubbing against air
This is the interesting one!!!!
Thrust – created
by engines
Weight – caused by mass
of the aircraft
Force Interactions
• To move forward what must be true?
• To lift off of the ground what must be true?
• How is lift created?
Force Interactions
• To move forward what must be true?
– Thrust must be greater than drag
• To lift off of the ground what must be true?
– Lift must be greater than weight
• How is lift created?
– Due to the curvature of the aircraft wing the air flows
over the top of the wing faster than the bottom of the
wing. Air flowing faster creates a lower pressure so
the wing is pushed up by the higher pressure on the
underside of the wing
Lift from a Wing
Pressure
From air
Aircraft
Motion
Air is accelerating around
top of wing – drops pressure
wing
Pressure
From air
Since pressure is
lower on top than
on the bottom of
the wing, the wing
is pushed up!!!
Quiz
Quiz
• What is a force?
__________________
• What are two examples of a
force?
__________________
__________________
• What is energy?
__________________
• What are two types of
energy?
__________________
__________________
• What is the sum of
potential and kinetic
energy?
__________________
Name______________
• What type of energy is stored
when a spring is compressed?
____________________
• What is a constant in the
spring experiment?
______________________
• When the spring is released
what type of energy is
created?
____________________
• Extra Credit: What is another
way to store energy in a
spring other then compressing
it?
____________________
KEY
Quiz
• What is a force?
Action that causes something to
speed up or slow down, like a
push or pull
• What are two examples of a
force?
Gravity, spring, and friction
• What is energy?
Ability to do work
• What are two types of
energy?
Potential, kinetic, mechanical,
chemical, and electrical
• What is the sum of
potential and kinetic
energy?
Mechanical energy
Name______________
• What type of energy is stored
when a spring is compressed?
Potential energy
• What is a constant in the
spring experiment?
The stiffness of the spring
• When the spring is released
what type of energy is
created?
Kinetic energy
• Extra Credit: What is another
way to store energy in a
spring other then compressing
it?
Lift it up – stores potential energy as
it is moved against the force of
gravity
Driving to Colorado Springs
Greenbriar West Elementary
By Darren McKnight
Fall 2004
Friction – Key Points
• What is friction?
• What makes friction greater?
• What makes friction less?
• What are examples of friction?
Friction
• Friction is rubbing – force between two surfaces
that goes against motion of object
– create heat or
– slow down motion or
– Both
• Rough surfaces makes friction greater while
smooth surfaces make friction less
• What are examples of friction?
•
•
•
•
Rubbing hands together to get warm
Putting sand on the road to prevent cars from sliding
Newspaper sliding across the driveway
Any more?
Friction
• Three items determine the friction force
– YES, FRICTION CREATES A FORCE!!!
• 1. Goes against the motion
• 2. Greater if surfaces are rough ; less is surfaces are smooth
• 3. Friction increases as mass of object increases
• If we slid a book across the two surfaces below,
on which one would the book go farther?
• Draw the forces on the book (pick one).
A
B
Friction
• If we slid a book across the two surfaces
below, on which one would the book go
farther?
A
Book (gravity)
Friction
A
Table
Force Due to Friction
• Force due to friction, Ff
– Ff = m * N
• Where m = coefficient of friction (constant)
• Where N = mg (weight of the puck acting in
opposite direction)
• If the surface is smoother is the coefficient
of friction larger or smaller?________
Friction Quiz
• Is friction a force? (Circle one) Yes No
• Does friction make an object move faster or does it
oppose motion (I.e slow it down) ? ______________
• What is the result of friction on spacecraft when they
come back through the atmosphere?
________________________________________
• If an object has a low coefficient of friction is it
smooth or rough? _______________________
Friction Quiz
• Is friction a force? (Circle one) Yes No
• Does friction make an object move faster or does it
oppose motion (I.e slow it down) ? _opposes motion_
• What is the result of friction on spacecraft when they
come back through the atmosphere? ____it heats up
the surface to very high temperatures______
• If an object has a low coefficient of friction is it
smooth or rough? ____smooth________________
Going to the Top of Pikes Peak
Greenbriar West Elementary
By Darren McKnight
Fall 2004
Potential and Kinetic Energy –
Key Facts
• What is energy?
• What is potential energy?
• What is kinetic energy?
Potential and Kinetic Energy –
Key Facts
• What is energy?
– Ability to do work
• Potential energy – “stored” energy
– How can we “store” energy?
• Kinetic energy – energy of movement
– Ask - How is potential energy converted into kinetic
energy?
Potential Energy
Does the ball
have any stored
energy here?
Does the ball
have any stored
energy here?
Potential Energy
Does the ball
have any stored
energy here?
Does the ball
have any stored
energy here?
NO
YES, we moved the ball
against gravity (did work)
Force Review
What forces are acting on the ball while we
hold it still above the floor?
Draw and label them.
Force Review
Force due to gravity
Which force is greater?
They are the same, that is why
the ball is not moving!!!
Force of the hand
Potential Energy
What happens when we let go
of the ball?
If the ball is to move show the
direction of the ball.
Label the forces on the ball!!!!
Potential/Kinetic Energy
Gravity
velocity
What happens when we let go
of the ball?
It starts to fall – has kinetic energy
If the ball is to move show the
direction of the ball.
Label the forces on the ball!!!!
Air
Gravity is larger force than
resistance
air resistance
Energy Summary
• What is the sum of potential and kinetic
energy?
• What are two other types of energy?
–
–
Energy Summary
• What is the sum of potential and kinetic
energy?
– Mechanical energy
• What are two other types of energy?
– Electrical energy: uses negative charge (e.g.
toaster)
– Chemical energy: uses chemical reactions
(e.g. battery)
Energy – Key Facts
• What is energy?
• What is potential energy?
• What is kinetic energy?
• What is the sum of potential and kinetic energy?
• What are two other types of energy?
–
–
Energy – Key Facts
• What is energy?
– Ability to do work
• Potential energy – “stored” energy
– How can we “store” energy?
• Kinetic energy – energy of movement
– Ask - How is potential energy converted into kinetic energy?
• What is the sum of potential and kinetic energy?
– Mechanical energy
• What are two other types of energy?
– Electrical energy: uses negative charge (e.g. toaster)
– Chemical energy: uses chemical reactions (e.g. battery)
Going to the Pool
Greenbriar West Elementary
By Darren McKnight
Fall 2004
Let’s Go Play!
• Liquid, gas, and solid
• Floating
• Swim races across the pool – 25m vs 10m
Last Night in the Hotel
Greenbriar West Elementary
By Darren McKnight
Fall 2004
Dad Wants a Cup of Coffee
Electricity Basics - Charge
• Atoms are made of neutrons, protons, and
electrons
– Electrons have negative charge
• Electrons are on the outside of the atom and are
easily knocked off
• When electrons are knocked off then an object
gets “charged”
– Positive if the electrons are knocked off
– Negative if the electrons that are knocked off cling to
the object
Materials Related to Charge
• Some materials hold their electrons very tightly
– Electrons do not move through them very well.
– These things are called insulators.
• Plastic, cloth, glass and dry air are good insulators.
• Other materials have some loosely held electrons,
which move through them very easily.
– These are called conductors.
• Most metals are good conductors.
Static Electricity
• How can we move electrons from one place to
another? _____________
• As electrons move from one atom to another…
– Some atoms get extra electrons - net negative charge.
– Other atoms lose electrons – net positive charge.
– When there is an imbalance of positive and negative
charges like this, it is called static electricity.
Static Electricity
• How can we move electrons from one place to another?
– Rub two objects together. If they are made of different materials, and are
both insulators, electrons may be transferred (or moved) from one to the
other.
– The more rubbing, the more electrons move, and the larger the charges built
up.
• Scientists believe that it is not the rubbing or friction that causes electrons to
move. It is simply the contact between two different materials. Rubbing just
increases the contact area between them.
• As electrons move from one atom to another…
– Some atoms get extra electrons - net negative charge.
– Other atoms lose electrons – net positive charge.
– When there is an imbalance of positive and negative charges
like this, it is called static electricity.
Charged Particle Behavior
• If two things have different charges, they attract, or pull
towards each other. If two things have the same charge,
they repel, or push away from each other.
– If they push each other what must there be? ________________
– What is the size of this “push” dependent on? ___________
Charged Particle Behavior
• If two things have different charges, they attract, or pull
towards each other. If two things have the same charge,
they repel, or push away from each other.
– If they push each other what must there be? force
– What is the size of this “push” dependent on? Charge and
distance between the charges
• FORCE – Coulomb’s Law
F = k (Q1 Q2)/d2
Real Life Observations
• So, why does your hair stand up after you
take your hat off?
Real Life Observations
• So, why does your hair stand up after you take
your hat off?
– When you pull your hat off, it rubs against your hair.
Electrons move from your hair to the hat.
– Now each of the hairs has a positive charge. Things
with the same charge repel each other.
– So the hairs try to move away from each other.
– The farthest the hairs can get is to stand up and move
away from each other.
Electricity – Use Physics for Good
• “Static” electricity is about charges that just
hang around (I.e. static)
• Electricity, as we know it, takes advantage
of moving charges to do work
– What do we call moving charges? __________
– What causes these charges to move?
______________________________________
Electricity – Use Physics for Good
• “Static” electricity is about charges that just
hang around (I.e. static)
• Electricity, as we know it, takes advantage
of moving charges to do work
– What do we call moving charges? CURRENT
– What causes these charges to move?
ELECTROMOTIVE FORCE OR VOLTAGE
Electricity Basics – V, i, R
• Voltage is the amount of electrical force measured
in volts
– Much like potential energy
– A charged particle will accelerate across a voltage
difference like a ball being released that is then acted
upon by gravity
V1
V0
-
Voltage difference created by the
two posts of a battery thus causing
charges to flow (I.e. CURRENT)
Electricity Basics – V, i, R
• If you want charge to flow in a wire (I.e. electricity)
then the flow of charges is called current
– Current = i, measured in amperes (or just amps)
• A wire will not let charges flow without some
resistance to their flow, this resistance is called
resistance!!!
– Resistance = R, measured in ohms
– Resistance is like “microscopic” friction
V=iR
Ohm’s Law
Effects of Current
• There are two effects of current
– Heating effect
• “Microscopic friction” creates heat
– Dissipates power (I.e. consumes energy over time): toaster
– Magnetic effect
• Moving charges create a magnetic field
– Used in motors and transformers
– Makes electricity generation possible
(which is the production of current)
– Spinning turbine (powered by steam, wind, water
or many other ways) turns electromagnets
that are surrounded by heavy coils of copper
wire inside generators that create magnetic
field that causes electrons to flow – CURRENT!
Types of Current
• Direct Current (DC)
– Current flows in the same direction all of the time
• Batteries create DC, usually lower voltages
• Alternating Current (AC)
– Current direction is reversed in direction at regular
intervals (e.g. 60 Hz – changes direction 60 times a
second - in your house)
• Electricity used in your home from outlets, higher voltages
(120V)
• Which is better?
– DC is more efficient so why do we all have AC in our
houses?_______________________________
Types of Current
• Direct Current (DC)
– Current flows in the same direction all of the time
• Batteries create DC, usually lower voltages
• Alternating Current (AC)
– Current direction is reversed in direction at regular intervals
(e.g. 60 Hz – changes direction 60 times a second - in your
house)
• Electricity used in your home from outlets, higher voltages (120V)
• Which is better?
– DC is more efficient so why do we all have AC in our houses?
For safety reasons, if you grab a high voltage DC line the body
will clamp up and not let go, many more electrocutions – all
devices driven to AC after original poor safety and human
response to DC
Power
• Power is measured in Watts
– 1500 Watt blow dryer, for example
• P = i V = current x voltage = V2 / R
• We have a 40W light bulb in your
house…
– How much current is flowing
through the light bulb?________
– What is the resistance in the light
bulb? ____________
Power
• Power is measured in Watts
– 1500 Watt blow dryer, for example
• P = i V = current x voltage = V2 / R
• We have a 40W light bulb in your
house…
– How much current is flowing
through the light bulb?
P=iV so i=P/V=40W/120V=0.33amps
– What is the resistance in the light
bulb?
V=iR so R=V/i=120V/0.33amps=360 ohms
or
P=V2/R so R=V2/P=(120V)2/40W=360 ohms
Electricity Basics
• What are materials that easily pass current?
• What are materials that do not easily allow
current to flow?
• Can you give examples of each one?
Electricity Basics
• What are materials that easily pass current?
– Conductors
• What are materials that do not easily allow current
to flow?
– Insulators
• Can you give examples of each one?
– Conductor: copper, steel, etc.
– Insulator: wood, glass, clay, etc.
Electric Circuits
• A series circuit has the same
current flowing through all
components
V
– If one component fails then
current stops
• A parallel circuit has the
same voltage drop across
each component
– If one component fails or is
disconnected it does not
prevent the flow of current to
other components
i
i
i
i
i
i1
i2
i3
V
i
i = i1 + i2 + i3
Electric Circuit - Problem
• For the circuit to the right:
– Are the two resistors in series or in parallel?
___________
– What is the total resistance of the circuit?
__________
– What is the current flowing through the circuit?
___________
– What is the power dissipated at the first element
(I.e. the 360 ohm resistance – like a light bulb)?
_______
– Do you think the circuits in your house are
wired in series or parallel and why? ____
_________________________________
_________________________________
R= 360 ohms
120V V
R= 360 ohms
Electric Circuit - Problem
• For the circuit to the right:
– Are the two resistors in series or in parallel?
R= 360 ohms
SERIES – each have same current flowing through them
– What is the total resistance of the circuit?
120V V
720 ohms – just add together
– What is the current flowing through the circuit?
V=IR so I=V/R=120V/720ohms=0.166 amps
R= 360 ohms
– What is the power dissipated at the first element (I.e. the
360 ohm resistance – like a light bulb)? P=I2R (since we
know both of these) P=(.166amps)2x(720ohms)=20W
– Do you think the circuits in your house are wired in series
or parallel and why?
Parallel because (1) if in series than if one system stops
working then current stops flowing and (2) the 120V
system would provide varying power to light bulbs rated
at the same power based on resistance – like this
example, the “40W” light bulb (I.e. 360ohms) only “gives
off” 20W (would be dimmer than hoped for)
Science on Vacation!
• Science helps you to learn how to describe
what is going on around you!
• Think – Experiment – Observe
– Just like you do with sports, friends, sledding,
reading, etc.
• Do not give up when you first do not
understand something
– Concentrate, draw a picture, propose a solution
Think, Experiment, Observe
Spring 2004 5th Grade Greenbriar West