how does understanding the science and technology of heat and temperature improve the quality of our...
TRANSCRIPT
How does understanding the
science and technology of heat and temperature
improve the quality of our
lives?
What is heat?
How hot is hot? (hands in water test) Hypothesis?
p204
What is heat?
What if heat was energy…(ability to move, do work, or cause changes) how would you explain the hot and cold hands?
What is heat?
Is there such a thing as cold?
What is heat?
Heat is the transfer of energy.
This is also called thermal energy.
What is heat?
Heat will always go from high energy to low energy.
What is heat?
Which way will the heat go in the following examples? (whiteboards)
1) Sleeping in your sleeping bag outside on a cold night.
What is heat?
Which way will the heat go in the following examples?
2) Putting your clothes in the dryer.
What is heat?
Which way will the heat go in the following examples?
3) Freezing ice cubes in the fridge…
What is heat?
True or False
Energy is measured in celsius.
What is heat?
True or False
Energy is measured in celsius.
FALSE! Energy is measured in joules. Which means heat is measured in joules…
What is heat?
True or False
All substances can transfer and hold the same amount of heat.
What is heat?
True or False
All substances can transfer and hold the same amount of heat.
FALSE! – Each substance has its own ability to transfer and hold heat….specific heat capacity.
What is heat?
True or False
If the amount of a substance is increased, then the amount of heat it has will increase.
What is heat?
True or False
If the amount of a substance is increased, then the amount of heat it has will increase.
TRUE – Eg) A match and a fire
What is heat?
But a match and a fire have the same temperature!
Whaaaat?
What is heat?
To really understand heat, we have to get down to the particle level. P203
What is heat?
The particle model of matter
1) All substances are made of tiny particles.
What is heat?
The particle model of matter
1) All substances are made of tiny particles.
2) The particles are always in motion.
What is heat?
The particle model of matter
1) All substances are made of tiny particles.
2) The particles are always in motion.
3) The particles have spaces between them.
What is heat?
The particle model of matter
1) All substances are made of tiny particles.
2) The particles are always in motion.
3) The particles have spaces between them.
4) The particles will collide with eachother.
What is heat?
When these particles collide, they can transfer energy….HEAT!
What is heat?
As the particles move faster, they absorb energy.
As the particles move slower, they lose energy.
(Get up and try it!)
How can this be related to changes in state? p220
What is heat?
The average speed of molecules can be measured
using
What is heat?
The average speed of molecules can be measured
using
TEMPERATURE
What is heat?
The average speed of molecules can be measured
using
TEMPERATURE
What is heat?
Temperature is measured using thermometers that convert the average kinetic energy to a scale.
ie. Glass thermometers with liquids, solid thermometers like meat thermometers, electric thermometers (thermocouples)
What is heat?
Temperature is measured using
a) degree Fahrenheit oF
What is heat?
Temperature is measured using
a) degree Fahrenheit oF
b) degree Celsius oC – based on the boiling and melting point of water
What is heat?
Some measurements of temp. 0F 0C
The same -40 -40
Boiling point of water 212 100
Freezing point of water 32 0
What is heat?
Temperature is measured using
a) degree Fahrenheit oF
b) degree Celsius oC
c) Kelvin - based on the predicted temperature of particles if they stopped moving. Absolute zero
What is heat?
0 K = -273.15 0C
370C =
Condensation of water?
Melting point of water?
Coldest recorded Canadian temperature ?
Hottest recorded Canadian temperature?
p 198
What is heat?
Temperature a) Is NOT heat!
b) Cannot be used to measure heat directly!
c) But…If the temperature increases, then the energy increases.
What next?
Now we know how heat works Depends on amount of substance
Depends on type of substance
Depends on average speed of the particles (temperature)
Let’s explore what happens to substances when we add or remove energy…
P210-216 (solid, liquid, gas)
Applications ie. Thermostats, cracks in pavement, liquids? Why is water unique? Expand when frozen, 40C in lakes,