Activities from the ALISON Guide to Heat and Energy Activities for the Classroom Developed by Todd...

Activities from the ALISON Guide to Heat and Activities from the ALISON Guide to Heat and Energy Activities for the ClassroomEnergy Activities for the Classroom

Developed by Todd Hindman at the Developed by Todd Hindman at the

Anvil City Science Academy (Nome, AK)Anvil City Science Academy (Nome, AK)

This presentation covers the following topics:• Understanding the Heat Capacity of Water• Thermal Resistance• Latent Heat• Temperature Gradients

Add HeatAdd Heat1. Describe the curve of the lines on your graph.

Where is it the most steep? Most gradual?2. If you are adding a constant amount of heat

every minute, the temperature should increase at a constant rate.

a) Do you agree or disagree with this statement? Why?

b) Does our data support this statement? Explain.

3. Give some possible reasons why the temperatures of the two beakers did not increase at the same rate.

Todd Hindman (Anvil City Science Academy, Nome AK.)

Hot RodsHot RodsMetal A B C D

Tstart

Tend

T

Mass of water

Qwater


Hot Rods cont.Hot Rods cont.Heat is transferred from warm to cold until

equilibrium is reached.

Q = m x T x sh

Q = amount of heat transferred (in calories)m = mass of substanceT = temperature change (Tend – Tstart)sh = specific heat, known value for every

substance (water = 1 cal/gºC)


Hot Rods cont.Hot Rods cont.

So … how hot was the rod before it was put in the water?

How many degrees did the water change when the rod was added?

How many degrees did the metal change when added to the water?

What does this mean?


How hot was the rod?How hot was the rod?

Q = m x T x shQ = 114 x T x 0.11Q = 114 x 0.11 x (35.7 – Tstart)-3078 = 114 x 0.11 x (35.7 – Tstart)-3078 = 12.54 (35.7 – T)-245.5 = 35.7 – T-281.2 = -TT = 281.2

Mass of Steel rod = 114g

Specific Heat of Steel = 0.11


Hot Rods cont.Hot Rods cont.

1. The HEAT CAPACITY for water and metal are different. Which has a high heat capacity? Low?

2. How does this relate to a lake during freeze up or thaw?

3. Do a lake and the air around it ever reach equilibrium? Explain.


Thermal ResistanceThermal ResistanceStyrofoam Glass

Tstart

Tend

ΔT

Volume of water (ml)

80 80

Qwater


Thermal Resistance is …Thermal Resistance is …

• The ability of a substance to resist the flow of heat through it

• A measure of the insulating abilities of a substance

• How quickly heat energy can pass through a substance


Thermal Resistance Questions:Thermal Resistance Questions:

1. What does a negative number for Q mean?

2. What has a bigger thermal resistance, glass or styrofoam?

3. What substance may add thermal resistance to a frozen lake and cause the ice to form slower?


Thermal Resistance of 3 MetalsThermal Resistance of 3 Metals

Metal 1 2 3 4 5 6

Steel

Cu

Al

What does this data tell you about the thermal resistance of metals? What did you learn about thermal resistancetoday? (Write 2-3 sentences.)


Temperature GradientTemperature GradientTime Hot

#1Cold #1

H-C #1

Hot #2

Cold #2

H-C #2

0

1

2

3

4

5

…15

500ml in tub (hot)80ml in beaker (cold)


Temperature GradientTemperature Gradient

• A temperature gradient is a difference in temperature across a given distance

• d = distance (meters)

d

TT startend −


Temperature Gradient QuestionsTemperature Gradient Questions

1. How were trial 1 and trial 2 different? How were they similar? Which trial had a bigger temperature gradient?

2. Describe or draw the temperature gradient on a frozen lake?

3. How do changes in temperature gradient effect ice growth? When will ice grow the fastest?

4. Calculate the amount of energy in calories added to the cold water for Trial 1 and Trial 2. Show your work.

5. Which trial had the fastest rate of energy transfer? (hint: rate is calories divided by time to reach equilibrium)


One More Time …One More Time …Time Hot Temp Cold Temp

0

0:30

1:00

1:30

2:00

… 5:00

500 ml hot in tub

Calculate the amount of energy in calories added to the cold water.

How does this compare to Trial 1 and Trial 2?


Latent HeatLatent HeatHot Water (Tub) Ice Water (Cup)

Volume (ml) 250

Tstart (ºC) 0

Tend (ºC)

ΔT (ºC)

Q (calories)


Latent Heat NotesLatent Heat Notes

• Phase Change – physcial change from one state to another (solid, liquid, gas)

• Latent Heat – energy required to change the state of matter– Heat of Fusion – amount of heat needed to

change a solid to a liquid– Heat of Vaporization – amount of heat needed

to change a liquid to a gas


Designing a Lake Ice StudyDesigning a Lake Ice Study

Goal: to figure out how much heat (or energy) in calories is being transferred from the water to the atmosphere

Challenge: You are being paid boo-koo bucks to design a study that will measure (on a regular basis) how much energy is leaving the lake.

Questions:• What measurements do you need to take?• How will you do this? What will the procedure be? (How

often? Where? With what?)• What are some potential problems with your procedure?

What could mess it up?


Heat & Ice EssayHeat & Ice Essay

Wayne has just moved to Alaska from Texas. He is amazed by the thick layer of ice found on Alaskan lakes in the winter. Explain to Wayne why ice forms on the lake. Describe the variables that determine how thick the ice will be.

** 2-3 paragraphs, use science vocabulary!


Activities from the ALISON Guide to Heat and Energy Activities for the Classroom Developed by Todd...

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