Transcript Section 10.1 Energy, Temperature, and Heat

Section 10.1
Energy, Temperature, and Heat
Learning Objectives
1. To understand the general
properties of energy
2. To understand the
concepts of temperature
and heat
3. To understand the
direction of energy flow as
heat
Section 10.1
Energy, Temperature, and Heat
What do we know about energy?
• It’s not matter / made of atoms
• It is needed for motion
• It is needed for life
• We get it from the chemical bonds in food molecules
• Matter contains energy  atoms & molecules, chemical
bonds
• It comes in many forms: heat, light, motion
• It can move from one place to another and change from
one form to another
• Modern societies use energy from fossil fuels, nuclear
processes, wind power, solar power, chemical reactions
– these can all be used to make electricity
Section 10.1
Energy, Temperature, and Heat
A. The Nature of Energy (pictures not in notes)
• Energy is the ability to do work or produce heat.
Potential energy
Energy of position
Kinetic energy
Energy of motion
Section 10.1
Energy, Temperature, and Heat
A. The Nature of Energy
• Law of conservation of energy
– Energy can be converted from one form to another but
can neither be created nor destroyed.
Section 10.1
Energy, Temperature, and Heat
WATER HEIGHT 
POTENTIAL ENERGY
WATER MOVES 
KINETIC ENERGY
Section 10.1
Energy, Temperature, and Heat
KINETIC ENERGY IN WIND
CAN BE CONVERTED INTO
ELECTRICAL ENERGY
FLOWING ON A WIRE
Can you tell kinetic energy from potential energy?
Disclaimer: The video clip you are about to watch shows
kids engaging in a dangerous activity (free running) that
is likely to result in bodily injury; I do NOT recommend
this. It does provide us with a beautiful illustration of
kinetic and potential energy!
http://www.youtube.com/watch?v=voB6WiP83NU
Section 10.1
Energy, Temperature, and Heat
How does heat energy flow?
Section 10.1
Energy, Temperature, and Heat
Biology Flashback
Mammals are homeothermic
– they keep a constant body
temperature even though the
environmental temperature
changes.
Why must we use energy to
keep our bodies warm?
Heat flows from where there
is more to where there is
less…
Section 10.1
Energy, Temperature, and Heat
B. Temperature and Heat (pictures not in notes)
• Temperature is a measure of the random motions of the
components of a substance.
Hot water
(90. oC)
Cold water
(10. oC)
Section 10.1
Energy, Temperature, and Heat
B. Temperature and Heat
•
Heat is a flow of energy between two objects due to a temperature difference
between the objects.
– Heat is the way in which thermal energy is transferred from a hot object to a
colder object
– If a temperature gradient exists, heat will flow (if it can) until the system
reaches equilibrium (same temperature all over)
Hot water
(90. oC)
Cold water
(10. oC)
Water
(50. oC)
Water
(50. oC)
Section 10.1
Energy, Temperature, and Heat
C. Exothermic and Endothermic Processes
(not in notes)
• System – part of the universe on which we focus attention
• Surroundings – everything else in the universe
• Burning a match
Section 10.1
Energy, Temperature, and Heat
C. Exothermic and Endothermic Processes
(picture not in notes)
• Exothermic – energy flows out of the system
• Endothermic – energy flows into the system
Section 10.1
Energy, Temperature, and Heat
Ex.: Metabolic Reactions
• Can be exothermic or
endothermic
– Exothermic reactions
produce heat to maintain
body temperature
– Endothermic reactions
require energy to occur:
• Break down food  release
energy (exergonic)
• Thinking, moving, building
proteins, etc.  absorb
energy (endergonic)
Section 10.1
Energy, Temperature, and Heat
C. Exothermic and Endothermic Processes
(notes summary)
• Exothermic – energy flows out of the system
• Endothermic – energy flows into the system
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