1 Heat
Unit 6: Heat
2 Heat
What is heat?
Water boils at 100◦ C
Lava has an average temperature of
1000◦ C
Sparklers burn at 2000◦ C
3 Heat
What is heat?
Why would you be severely
burned by lava (or even boiling
water)
t ) but
b t th
the sparks
k from
f
the sparkler are harmless?
4 Heat
What is heat?
Are there limits to how hot or how cold
something can get?
Why does
Wh
d
a tile
til floor
fl
feel
f l cold
ld while
hil th
the
carpeted floor feels warm at the same
temperature?
Why does hot air expand by hot water
vapor contracts?
Why does ice form on the top of the
pond, not the bottom?
5 Heat
What is heat?
Do you have any questions about heat or
temperature?
6 Heat
Learning Goal:
I can define temperature and heat and
can describe the relationship between
them.
them
you already
y know, could
Based on what y
you:
Define heat?
D fi
Define
ttemperature?
t
?
Describe how they are alike and how they
are different?
7 Heat
The Kinetic Theory of Matter
What does kinetic relate to?
Kinetic = Motion
What is matter?
Matter = Particles with mass (atoms)
What is a theory?
Theory = a scientifically tested idea
8 Heat
The Kinetic Theory of Matter
The particles
Th
ti l that
th t make
k up matter
tt are
always moving.
They have kinetic energy because of their
movement.
They move in different ways:
Straight line (translation)
Rotating (Spinning)
Vibrating
9 Heat
The Kinetic Theory of Matter
Particles
P
ti l can have
h
allll three
th
types
t
off kinetic
ki ti
energy (translational, rotational and
vibrational))
Particles also have potential energy from
attractions or repulsions between each
other
Thermal Energy is the total energy in a
particular substance and is thought of as
internal energy
10 Heat vs Temperature
Temperature
When you hit a nail with a hammer, it
becomes warm. Why?
When you light a candle in a jar,
jar the jar
becomes warm. Why?
In each of these examples, the particles
gain kinetic energy.
I general,l th
In
the warmer an object,
bj t the
th more
kinetic energy its atoms possess.
11 Heat vs Temperature
Temperature
Temperature, which is the degree of
“hotness” or “coldness” of an object, is
proportional to the average translational
kinetic energy of the atoms and
molecules make up the substance.
Temperature is not a measure of the total
kinetic energy in a substance.
substance
12 Heat vs. Temperature
Heat vs. Temperature
Heat
Temperature
1
1.
Thermal Energy
KE + PE
1
1.
2.
For the whole
substance
2.
3.
Measured in
calories or joules
3.
Average
Translational Kinetic
Energy
For each particle in
the substance
Measured in
degrees
13 Heat vs. Temperature
Heat vs. Temperature
Example: the Fourth-of-July-type sparkler
Th sparks
The
k that
th t fly
fl from
f
the
th firework
fi
k and
d
strike your face have temperatures in
excess of 2000°C, but they don’t burn.
Because the thermal energy of the sparks is
extremely low. Even though the kinetic
energy/particle is very high
high, only a few
molecules actually touch your skin.
14 Heat vs. Temperature
Heat vs. Temperature
1 liter of boiling
water
2 liters of boiling
water
Temperature?
Temperature?
Same
Heat?
Same
Heat?
Less
More
15 Heat
Reflection
Mark your calendar!
Today’s learning goal:
I can define temperature and heat and can
describe the relationship between them.
Using the scale, how do you think you are
doing with the concept?