Thermodynamics

Heat Equivalent

Electrical Equivalent of Heat

Fill clear jar with water and insert light bulb.

Measure voltage and current to the bulb.

Measure the raise in temperature for the water.

Introduce India ink into the water so more energy is absorbed.

Repeat measurements.

Electrical equivalent of heat apparatus (Pasco TD-8552)

Heat-02

Coming Soon

Heat Equivalent

Mechanical Equivalent of Heat

Mechanical equivalent of heatapparatus (Pasco TD-8551A)

Thermal Conductivity

Ice Melting Blocks

Pass out blocks to class. Each person gets both types of blocks.

One block feels warm the other feels cold.

Ask which one will melt the ice faster.

Place ice on blocks and wait.

Ice melting blocks

Crushed ice

Paper towels

Thermal Conductivity

Wax Melting

Wrap ends of each piece of metal in small strip of wax.

Boil water using hot plate and pour into the reservoir.

Wax will melt at different rates for different metals.

Heat conductivity apparatus

Wax

Hot plate

Metal container

Water

Heat Capacity-01

Heat Capacity

Boil Water in Paper Cup

Fill cup with water.

Hold cup with tongs in flame of propane torch.
(Hold over water bucket for safety.)
Don't use too much water or it will take forever to boil!

Paper cup

Tongs

Propane torch

Ignitor

Fire extinguisher

Water bucket

Thermal Expansion-01

Thermal Expansion

Ball and Ring

Ball will fit through ring when both are at the room temperature.
When heated, the ball no longer fits.

Metal ball w/handle

Metal ring w/handle

Propane torch

Igniter

Fire extinguisher

UMd - I1-12

Thermal Expansion-02

Thermal Expansion

Ball and Plate

Ball will not fit through plate when at room temperature.
Heat plate.

Ball fits through.

Metal ball w/handle

Metal plate w/handle

Propane torch

Igniter

Fire extinguisher

UMd - I1-11

Thermal Expansion-03

Thermal Expansion

Bi-Metal Bars

Each bar has a different metal on each side.

The metals have different coefficients of thermal expansion.

Heating with the torch will cause the bar to bend toward the metal which expands less.

Cooling back down will straighten it out.

Bi-metallic bars

Propane torch

Igniter

Fire extinguisher

Thermal Expansion-04

(see also:
Liquid
Nitrogen-09)

Thermal Expansion

Bi-Metal Bars

Each bar has a different metal on each side.

The metals have different coefficients of thermal expansion.

Cooling in liquid nitrogen will cause the bar to bend toward the metal which contracts more.

Heating back up will straighten it out.

Liquid Nitrogen

Bi-Metallic Bars

Thermal Expansion-05

(see also:
Liquid
Nitrogen-07)

Thermal Expansion

Balloon

Blow up a balloon and tie it off.

Ask the audience what will happen if the balloon is put into the liquid nitrogen.

Ask a volunteer to put the balloon in the dewer for a few seconds.

Bring the balloon back out and show to the audience.

Liquid nitrogen

Balloon

Tongs

Thermal Expansion-06

(see also:
Liquid
Nitrogen-08)

Thermal Expansion

Ball and Ring

Ball will fit through ring when both are at the room temperature.
When cooled, the ring no longer fits.

Liquid nitrogen

Metal ball w/handle

Metal ring w/handle

Simple Engine

Visible Stirling Engine

Place Stirling engine on top of cup (in contact with water works best).

Give engine a small spin to start.

Stirling engine

Cup full of ice water or heated water.

Thermoelectric

Heat to Electrical Energy

Place one leg of thermoelectric convertor into hot water and the other into cold water.

Fan begins to turn.

Thermoelectric convertor

Cup of hot water

Cup of cold water

Simple Engine

Electrical Energy to Heat

Pass a 3A current at 5V through the thermoelectric convertor.

One leg becomes warmer and the other becomes cooler.

Thermoelectric convertor

Power supply

Banana-banana cables

Adiabatic Compression

Compression Ignitor

Load compression ignitor with tissue paper or cotton.

Place plunger inside compression tube and place inside larger plastic container.

Push down very quickly.

Compression ignitor

Tissue paper or cotton ball

Vaporization

Pouring

Pour liquid nitrogen from dewer to display dewer, pour some on the floor, and then pour some in a clear cup.

Ask what is going on. Why is there so much vapor?

Liquid nitrogen

Display dewer

Clear plastic cup

Vaporization

Cold Vapor

Pour some liquid nitrogen into a tea kettle.

After a few second it will begin to whistle.

Ask your audience if the tea kettle is whistling is it hot or cold?

Liquid nitrogen

Tea kettle

Vaporization

Bottle and Stopper

Pour a little liquid nitrogen into the water bottle (or film canister) and plug with the rubber stopper.

Eventually the stopper will pop off of the bottle.

Hint: A little bit of water in the bottle helps speed up the process.

PRACTICE!

Warning: Do no jam the stopper onto the bottle or the bottle could explode instead.

Liquid nitrogen

Water bottle

Rubber stopper

Film Canister

Temperature

Scale Thermometer

Reveal to he audience the typical temperature range for everyday type of objects.

Stand on a chair (that won't roll) and unveil how cold liquid nitrogren is.

Hand-painted thermometer

Chair without wheels

Ignition

Suffocate a

Match 1

Ask the audience what will happen if you light a match and slow lower it into the dewer.

Light a match and stick it in the gas in the dewer.

It will suffocate and go out.

Liquid nitrogen

Long stick-match

Ignition

Suffocate a

Match 2

Very similar to Liquid Nitrogen-05.

Ask the audience what will happen if you pour the gas onto a lit match.

Carefully pour just the gas from the dewer onto a lit match.

Liquid nitrogen

Long stick-match

Liquid Nitrogen-07

(see also: Thermal Expansion-05)

Thermal Expansion

Balloon

Blow up a balloon and tie it off.

Ask the audience what will happen if the balloon is put into the liquid nitrogen.

Ask a volunteer to put the balloon in the dewer for a few seconds.

Bring the balloon back out and show to the audience.

Liquid nitrogen

Balloon

Tongs

Liquid Nitrogen-08

(see also: Thermal Expansion-06)

Thermal Expansion

Ball and Ring

Ball will fit through ring when both are at the room temperature.
When cooled, the ring no longer fits.

Liquid nitrogen

Metal ball w/handle

Metal ring w/handle

Liquid Nitrogen-09

(see also: Thermal Expansion-04)

Thermal Expansion

Bi-Metal Bars

Each bar has a different metal on each side.

The metals have different coefficients of thermal expansion.

Cooling in liquid nitrogen will cause the bar to bend toward the metal which contracts more.

Heating back up will straighten it out.

Liquid Nitrogen

Bi-metallic bars

Properties at Low Temperatures

Shatter a Flower

Put a flower into the liquid nitrogen and give several minutes for it to freeze.

Ask a volunteer to hit an unfrozen flower with a hammer.

Ask a volunteer to hit the frozen flower with a hammer.

(Wear goggles!)

Liquid nitrogen

Flower

Properties at Low Temperatures

Bouncy Balls

Put each of the balls into the liquid nitrogen and allow plenty of time to cool. (Do this early and continue with other demos then come back to this one.)

Ask the audience if each ball will bounce better, worse, or the same.

A) Ping pong ball - Little difference

B) Rubber ball - Some difference

C) Racquet ball - Big difference

D) Shatter the racquet ball against a solid surface.

Liquid nitrogen

Ping pong ball

Rubber bouncey ball

Racquet ball

Tongs

Good solid surface

Properties at Low Temperatures

Ring the Pewter Cup

Ring the pewter cup with a small hammer to show that it has more of a thud sound.

Put the pewter cup into the liquid nitrogen and allow plenty of time to cool.

After cooling the cup has a nice ring when tapped with the hammer.

Liquid nitrogen

Pewter cup

Tongs

Properties at Low Temperatures

Ultimate Ring Shooter

Shoot Al ring high in the air.
Cool the Al ring in the liquid nitrogen.

Shoot it again.

Ring shooter

Various rings (solid Al, slotted Al, plastic, iron)