Unit 6: Heat
Transcript of Unit 6: Heat
2 Heat
What is heat?What is heat?Water boils at 100◦ C
Lava has an average temperature of
1000◦ C
Sparklers burn at 2000◦ C Sparklers burn at 2000 C
3 Heat
What is heat?What is heat?Why would you be severely
burned by lava (or even boiling
t ) b t th k f water) but the sparks from
the sparkler are harmless?
4 Heat
What is heat?Are there limits to how hot or how cold Are there limits to how hot or how cold something can get?
Wh d til fl f l ld hil th Why does a tile floor feel cold while the carpeted floor feels warm at the same temperature?temperature?
Why does hot air expand by hot water vapor contracts?
Why does ice form on the top of the Why does ice form on the top of the pond, not the bottom?
6 Heat
Learning Goal:I can define temperature and heat and
can describe the relationship between themthem.
Based on what you already know, could y yyou:
Define heat?D fi t t ?Define temperature?Describe how they are alike and how they
are different? are different?
7 Heat
The Kinetic Theory of Matter
What does kinetic relate to?
What is matter?
Kinetic = Motion
What is matter?
Matter = Particles with mass (atoms)
What is a theory?
Theory = a scientifically tested ideaTheory a scientifically tested idea
8 Heat
The Kinetic Theory of MatterTh ti l th t k tt The particles that make up matter are
always moving.They have kinetic energy because of their They have kinetic energy because of their
movement.
They move in different ways:
Straight line (translation)
Rotating (Spinning)
VibratingVibrating
9 Heat
The Kinetic Theory of MatterP ti l h ll th t f ki ti Particles can have all three types of kinetic
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
TemperatureWhen you hit a nail with a hammer, it
becomes warm. Why?When you light a candle in a jar the jar When you light a candle in a jar, the jar
becomes warm. Why?
In each of these examples, the particles gain kinetic energy.
I l th bj t th In general, the warmer an object, the more kinetic energy its atoms possess.
11 Heat vs Temperature
TemperatureTemperature, which is the degree of
“hotness” or “coldness” of an object, is proportional to the average translational 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 substancekinetic energy in a substance.
12 Heat vs. Temperature
Heat vs. TemperatureHeat
1 Thermal Energy
Temperature
1 Average 1. Thermal EnergyKE + PE
1. Average Translational Kinetic Energy
2. For the whole substance
2. For each particle in the substance
3. Measured in calories or joules
3. Measured in degrees
13 Heat vs. Temperature
Heat vs. TemperatureHeat vs. TemperatureExample: the Fourth-of-July-type sparklerTh k th t fl f th fi k d The sparks that fly from the firework and
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 only a few energy/particle is very 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 Same
Heat? Heat?Less More