STATION 1
LIQUID HOT LAVA
PROCEDURES:
Observe the lava lamp for 45-60 seconds. Answer the following questions based on
your observations. Please do not move the lamp or touch the lamp. They can break
and may be HOT.
1. How is heat being transferred in the lava lamp (convection, radiation, or
conduction)? Hint: there may be more than one.
a. Convection: when the hot blobs move up through the liquid they are
transferring heat to the top of the lamp.
b. Conduction: when the air molecules (top of lava lamp) and liquid molecules
touch each other they transfer some heat. The base also touches the lamp and
heats a piece of metal inside the lamp.
c. Even a little Radiation- the lamp is not really touching the bottom of the
glass. Radiant heat transfer is occurring from the light bulb to the wax at the
bottom of the lamp through the glass.
2. Describe what is happening in the lava lamp as it relates to hot and cold air and
how they move in the atmosphere?
a. Hot air tends to rise and as it rises it cools. As the air cools, its density
increases and starts to fall back towards the ground. Once it goes back
towards the ground, it is warmed by the heat from the ground and starts to rise
again. This is one of the driving forces behind wind on our planet. Cool,
huh?
3. Why do the blobs of material go up then back down? What is happening in
terms of heat? Where does the heat from the rising blobs go once they get to the
top of the lamp?
a. They go up because they are being heated and their volume increases which
means the density decreases (spreads out and gets lighter). The less dense
blobs float upwards until they cool and fall back to the bottom of the lamp.
Most of the heat is lost to the air just outside the lamp.
b. Heat is being transferred to the blobs and they rise. That same heat is lost to
the atmosphere, which causes the blobs to sink back to the bottom because
their density increases as they cool down.
c. The heat flows to areas that are cooler (remember heat is what moves, not
coldness). The air right outside the lava lamp is cooler. The heat from the
lava lamp radiates outwards and also warms the air through conduction (the
air that is touching the top of the lava lamp gets warmer. This even results in
little convection currents of warm air rising (kind of like when you drive
through the desert and see the “heat” rising off the hot road.
4. Convection heat transfer can only happen in which of the three states of matter
(solid, liquid, or gas)?
a. Liquid or gas only. Solids do not flow. When solids flow, they are called
liquids. Try it sometime. Take frozen water (an ice cube) and see if it starts
to flow when you place it on the ground. Take liquid water (tap water) and
pour it on the ground. Notice how the liquid water “flows”. Now, take a hot
(not too hot as to burn you through conduction) shower (make sure this okay
with your parents) and watch the steam rise (flow). Cool, huh?
5. Where does rising air get energy to rise? What is the source of most all energy
on our planet?
a. The sun. The sun, the sun, the sun
STATION 2
Foiled Again
(Black vs. White vs. Foil)
PROCEDURES:
Without touching the sheets covering the thermometers, look at the three sheets
(black, white, and foil) and record the temperature for each. Answer the questions
that follow.
QUESTIONS:
1. Which sheet has the highest temperature reading? Why?
Which has the lowest? Why?
a. Black. This is because black absorbs heat better than white or the foil. Black
is the absence of color (it is not a color really) the reason something appears
black is because no light is reflected back to your eyes. All the colors are
absorbed into the black object. Light is a form of energy. This is why black
gets hotter than other colors (it is absorbing all that energy).
b. The foil. This is because the foil reflects most of the light (and heat energy)
back into the atmosphere. This is the same thing that happens on overcast and
cloudy days. That is why it is cooler on cloudy days compared to clear days.
Amazing.
2. Which land type would you expect to find hotter at mid day (desert or snow
covered mountains)? Give at least two reasons why?
a. The desert. First, because it is a darker color than white (snow being
white). Second, areas where there is snow need to be cold so water can
freeze and become snow. Also, as you go up in elevation (the mountains)
the temperature drops. FYI-Temperature drops at approximately 10 F for
each 1000 feet you go up in elevation. This is assuming a whole bunch of
other things are not affecting the temperature (like humidity and other
weird things that I do not even understand).
3. If you were going out to build a house in the desert, what color and what
direction would you want the windows to face?
a. You would want a white or light color house. Your windows should have a
photochromic (it becomes lighter or darker depending on the amount of
light hitting the glass) or mirror tint on them as well.
b. Your windows should face northeast so that the midday sun does not heat
up you house like a giant greenhouse.
c. FYI-When you go skiing in the mountains you usually have ski resorts that
face north or northeast. Mammoth faces in this direction except for the
backside (to the right of the main lodge if you are looking up the mountain
or right of chair 23 (up to the Cornice) as you go up the mountain.
4. If you had to buy a Jeep to travel across the desert this summer, in search of
ultimate place to read a good book, what color would you want your new Jeep to
be? Why?
a. White or silver. It will stay cool in the sun (especially because you could
not afford the air conditioner or the convertible).
b. Black cars show dirt easily compared to white. Since you are in a desert,
there is too little water to wash your Jeep every week. This answered was
made possible by Bruce Kantelis. This is the reason he gave for not buying
the black Jeep.
5. What type of heat transfer is causing the thermometers to heat up? Write down
the temperatures of the three thermometers.
a. It is a combination of radiation and conduction. Radiation from the lamp
causes the paper or foil to absorb heat. The heat energy that is absorbed is
transferred to the thermometer through conduction. The thermometer is
touching the paper and or foil and absorbs heat from it.
b. White = 26 to 28, Black = 28 to 30, and Foil = 24 to 26 Celsius
6. Why is the desert so hot during the day and cold at night (think moisture here)?
a. It gets really hot in the day because there is little water in the air. Water is
a very, very good absorber of heat (it can store a lot of heat before
increasing in temperature). It has a high heat capacity. That is why the
radiator in most cars uses water to cool the engine verses air.
b. At night, the air in the desert is dry and has very little moisture in it to hold
heat. The temperature at night drops quickly because there is no way to
store the heat from the day.
STATION 3
The Thermometer Never Lies
PROCEDURES:
Use the readings on the three thermometers to answer the following questions
concerning temperature. There should be one thermometer in a test tube of water,
one in a mound of clay (putty), and one inside a test tube filled with air. Please do
not touch the thermometers. All that is required is to read the temperature from
each thermometer.
QUESTIONS:
1) Which thermometer has the highest reading (clay, water or air in the test tube)?
a) They should all be the same (21-25oC). For the most part, you should have
had a temperature about the low 20s C or the mid 70s F.
2) Which object would you think would feel the coolest if you touched it?
a) The water. This is because water is a very good absorber of heat (has a high
heat capacity). That is why you put a wet towel on your head when you have
a fever or want to cool down.
3) What is temperature a measure of?
a) It is a measure of energy (heat energy) in a substance. It just like showing you
how fast (like a radar gun) the molecules in a substance are moving.
4) Do the readings on the thermometers seem right? Explain?
a) Yes, because all three objects are in an environment (The classroom) that has
an air temperature of 21-25o C (70-77o F). We think water should be cooler
because it is what we use to cool things down (like ourselves). We usually do
not rub clay all over our skin to cool down Remember, water is good at
absorbing heat (high heat capacity) and that is why logic would have told
you that the water should have been the coolest (LOGIC was wrong this time.
Ironic?
No).
5) Why does the air get hotter than the ocean? Why does the ocean only change
about 200 F through out the year, but the air can go from over a 1000 F to 300 F in
our area?
a) This is due to the ability of water to absorb large quantities of heat (energy)
before rising in temperature. Try blowing on your hands with your hot breath.
You feel that it is hot (because it is easier (less energy is needed) to raise the
temperature of air compared to water). Do the same thing to a small cup of
water and see if you notice the temperature change (probably not unless you
cheated or something).
6) What does density have to do with heat conduction?
a) Things that have low densities tend to not absorb heat well (air, wood,
fiberglass insulation (mainly air)). Things that have higher densities tend to
absorb heat very well (metals). Air is a bad conductor of heat (low density
and little matter).
STATION 4
Heat by Touchy, Touchy
PROCEDURES:
Touch each of the three items on the counter (metal, plastic, and wood). Answer
the questions that follow.
QUESTIONS:
1) Which material feels the coolest? Why?
a) The metal. This is because metal is a very good conductor of heat (and
electricity for that matter). That is why we cook with metal pots and not
plastic or wood pots and pans.
2) How is heat being transferred when you touch one of the objects?
a) Conduction – heat by touchy, touchy
3) What is absorbing the heat? Your hand or the object?
a. The object is absorbing heat or energy from my hand. I am not absorbing cold
from the object. Heat is the only thing that flows (in the universe). That is
how ice cubes work. They absorb heat from your drink and in the process
melt. Cool, huh?
4) In the real world where does this type of heat transfer take place?
a) Conduction occurs when hot and cold air masses meet. It can also occur when
air is warmed by the heat from the ground (air molecules touching the earth)
on a hot day. It occurs when you cook food in a pan or lay down on warm
sand after being in contact with the cold water where through conduction with
the water you lose heat to the water.
5) Define the three types of heat transfer (short definition):
Conduction: heat transfer through touch
Convection: heat transfer through movement (flow) of a liquid or air.
Radiation: heat transfer through space (not matter) in the form of waves.
PART II
ove
THE L
METER (a.k.a. Mr. Love Bird)
Hold Mr. Love Bird’s belly with one hand (do not hold it too tight, it
may kill the love bird) watch what happens to the liquid. Answer the
questions that follow. Do not spend the entire time seeing if you are a good
lover. Please do not break.
1. What type of heat transfer is this? Explain why.
a. Conduction. Why not? It is conduction because your hand is touching
the glass. Heat is being transferred from your hand to the glass and into
the liquid. The liquid has a low boiling point (around 85o F to 95o F)
(water is 212o F or 100o C) and boils after a few seconds of being heated
by your hand. You could also say convection because the heated liquid
is moving up the tube and cools at the top and comes back down and
repeats the cycle over and over and over again.
2. What is happening to the liquid as you hold you hand against the bottom?
a. It is boiling because heat is being absorbed from your hand and
transferred to the liquid by direct contact. This causes some of the liquid
to evaporate (turn from liquid to gas).
STATION 5
Let There be Light
PROCEDURES:
Have your partner stand a few feet away (1-2 feet) from you. Turn on the light (little red
button on backside of lamp) and shine it towards your partner’s hand (but, do not pick
the light up). Turn off the light and switch with your partner. Repeat the above
procedures. Turn off the light before answering the questions that follow.
1. What type of heat transfer might this demo represent?
a. It is mainly radiation (like the sun to the Earth). There is a little conduction
(air molecules that are touching the glass) between the air molecules, but the
great majority of heat transfer is radiation (because the sun is rad and stuff).
b. FYI (It could be convection if a fan was blowing the heat away from the hot
metal parts and allowed to blow the warm air around the room).
2. Did you feel the heat from the light when standing 1-2 feet away?
a. Yes you did, yes you did.
3. Does this type of heat transfer need matter to occur? In what form is the heat
transferred?
a. No, it does not need matter or air to occur. It travels through space and
space is a vacuum (yes, space does suck because it is a vacuum).
b. The heat is being transferred in WAVES – HEAT WAVES.
4. Give an example of this type of heat transfer?
a. Tanning salon, heat lamps at McDonalds, the sun, or heat from a campfire.
5. Some people (Mr. Mathot) say that physics makes the world go around. Some
people (Mr. Mathot again) have just realized that the sun makes the world go
around. Explain what I mean by this. Use 3 to 86 sentences to explain.
a. All the energy on this planet (heat) came from the sun (except from heat from
inside the Earth). This includes all the planets, food, gas in our cars and
materials we use each day (that were once living). Energy from the sun is
what makes air and water heat up and move and that movement of air and
water is what creates weather on our beautiful planet. Oh yes, the suns
gravitational force is what keeps us in orbit along with our inertia.
STATION 6
PLASMA BALL
PROCEDURES:
Place your hand on top of the sphere. Use your observations of what is happening
and L O G I C to answer the following questions.
1. What happens when you put your hand on the sphere?
a. The “lightning” is attracted to where your hand is placed on the sphere. This is
because there is a buildup of negative charges on the metal ball inside the
sphere. Your hand is more positive than the middle, so it attracts the negative
charges (opposites attract, likes repel). The place where your hand is touching
starts to get warmer because energy is being transferred from the little light
bolts, to the glass, and then to where your hand is touching.
2. What type of heat transfer might this demo represent?
a. Conduction (heat transfer through contact). Your hand gets hot from touching
the glass if you keep it there long enough (but not too long).
3. Where is the heat coming from and then going to? In other words, what is
absorbing heat and from where is it absorbing the heat?
a. The heat is coming from the electrons (which have energy) that are hitting the
glass at the place where your hand is touching. This causes a buildup of
energy (heat) due to all of those little electrons colliding with the glass.
b. Your hand absorbs this energy from the plasma ball. The longer you keep
your hand there the hotter it will get because you are absorbing more energy.
4. Why does the sphere act as it does when you touch it (think about air compared
to your skin and which is the better insulator and which the better conductor of
electricity)?
a. The electrons are “looking” (seeking might be a better word) for the path of
least resistance. Your hand conducts electricity better than the gas in the
sphere. That is why lightning has a zigzag pattern and not a straight lightning
bolt (air is a good insulator and a poor conductor of heat and electricity).
(Bonus question & answer)
What is really happening in the plasma ball?
Electrons are building up in the center sphere and are being pushed towards the
glass. Now, the electrons really do not want to jump from the middle to the outside
of the sphere put the voltage is strong enough to get them moving. Remember, like
charges repeal. All this negative charge in the middle cause many unhappy
particles. There is not enough room for all this negativity so some of the electrons
are forced to leave.
The electrons do not like traveling through the gas because the gas does not
conduct electricity very well. It is an insulator. The reason you see light is because
the electrons in the gas are getting excited about all the hoopla and need to release
the extra energy they are receiving. They release the energy as light (photons).
The reason why the lightning goes towards your hand is because your hand is
a better conductor of electricity compared to the gas in the sphere or the glass
itself. Your hand has a positive charge compared to the charge inside the plasma
ball. NOTE: Some people attract the negative charges better than others do.
Don’t worry, it doesn’t mean you’re a good or bad lover (unlike the love meter).
BACKGROUND - Lightning
Lightning is caused by a buildup of electrical charges in the atmosphere. This
occurs when clouds rub past one another. Things in nature like to be balanced so
you get lightning. Use the plasma ball to assist you in answering the questions.
5. When is there lightning (what type of weather)? Where does lightning tend to
strike (what objects on the ground)? Where might you want to be in a lightning
storm?
a. During thunderstorms or unstable weather. This would be when two different
air masses meet.
b. It tends to strike tall objects (trees, building, and people standing up in open
fields) and metal objects (lightning rods). This is because it is looking for the
shortest path between the clouds and the ground (or the ground and the
clouds- about 10 to 20 % of lightning goes from the ground to the sky
(because of the buildup of charges in the ground). Remember, air is an
insulator and not a good conductor of electricity. You conduct electricity
better than the air.
c. Inside of a building, inside a car and not touching any metal parts, in a tight
ball in an open field. YOU DO NOT WANT TO HIDE UNDER TREES,
METAL THINGS OR LIE DOWN IN A FIELD (all very bad and potentially
deadly).
6. Why do you see lightning before you hear the thunder?
a. Light travels faster than sound. Light travels at 300,000 meters/second or
186,000 miles per hour and sound travels at 1200 km/h or 750 miles per hour.
You can tell how far lightning is by counting as soon as you see the lightning.
Once you hear the thunder, stop counting. Every 5 seconds is roughly equal to
1 mile away from you.
7. Where does lightning come from and go to (strike)? (more than 1 answer)
a. 50 to 70 % of lightning goes from cloud to cloud (like static cling in your
clothes drier), 20-30% from cloud to ground and 10-20% from ground to sky.