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Types of Energy
-kinetic, potential, chemical and thermal
-Law of conservation of energy
What is Energy?
It is the ability to do work or produce heat
 Exists in two forms
◦ Potential Energy – stored energy
◦ Kinetic Energy – energy of motion

Heat is Not the Same Thing As
Temperature!
 What
is Temperature?
 A measure of the average kinetic
energy of the particles in a
sample of matter.
Thermal Energy (Heat) is a Type of
Kinetic Energy

The energy formed when heat is flowing
from a warmer object to a cooler object is
called thermal energy
◦ The faster the particles move, the warmer the
matter can get
◦ Often represented by a Q for heat
◦ Q can be positive or negative depending on
whether an object is getting warmer or colder
◦ Example:
 matches
Chemical Energy is a Type of
Potential Energy

Energy that is stored in a substance
because of its composition is called
chemical energy
◦ Energy is stored in the bonds between atoms
◦ Examples:
 when plants take in radiant energy from sunlight
and store it as starches and sugars
Law of Conservation of Energy

Obeys the Law of Conservation of Energy
◦ In any chemical reaction or physical process, energy
can be converted from one form to another, but it is
neither created nor destroyed
 Called First Law of Thermodynamics
How do we measure energy and
use conversion factors?

Units
◦ calorie (cal) – the amount of energy required to
raise the temperature of one gram of pure
water by one degree Celsius
◦ Calorie (Cal) – is known as a food calorie or a
nutritional calorie.
1 Cal = 1000 cal
◦ Joule (J) – SI unit of energy and heat
1 J = 0.2390 cal
1 cal = 4.184 J
Example:
1 tablespoon of butter contains
approximately 100 Calories.
If we burn the butter to produce CO2 and
H2O then 100 Cal (100,000 cal) of heat
would be released.
Practice

How many J are in 100 cal?

How many Calories are in 65,000 J?
Heat Transfer

Heat always moves from a warmer place
to a cooler place.
◦ Hot objects in a cooler room will cool to room
temperature.
◦ Cold objects in a warmer room will heat up to
room temperature.

There are 3 types of Heat Transfer
Conduction – the transfer of energy
through direct contact.
Conduction requires
touching.
Example:
A spoon in a pot of hot soup becomes warmer
because the heat from the soup is transferred to the
spoon.
Convection – the transfer of heat by the
actual movement of the warmed matter.
•Heat energy is transferred in a gas or
liquid by movement of currents.
Convection
currents.
Does not occur in solids
Radiation

The heat that you can feel coming off an object.
◦ Heat is radiated from the sun
◦ Heat radiates from a hot object and you can feel that heat
without touching it.
With an infrared camera,
you can see how heat
radiates off this elephant.
Heat Transfer
How does heat behave?
How is energy transferred?
There are 3 ways that thermal (heat)
energy is transferred:
1. Conduction
2. Convection
3. Radiation