Energy
What happens in an ecosystem in terms of MATTER and ENERGY?
● Energy moves through an ecosystem, it changes form, but no new energy is created
● Similarly, as matter cycles within an ecosystem, atoms are rearranged into various
molecules, but no new matter is created.
● Matter and energy are conserved
What does Energy allow us to do?
● Energy allow us to do work and accomplish tasks, e.g.:
○ Move
○ Perform physical activities
○ Generate heat and light
○ Etc.
How does Energy manifest itself?
● Energy exists in different forms:
○ Mechanical energy (motion of objects - kinetic and potential energy)
○ Thermal energy (heat)
○ Chemical energy (energy stored in the bonds between atoms and molecules)
○ Electrical energy (energy associated with the movement of electric charges -
wires)
○ Radiant energy (microwaves)
Is Energy always conserved? Is Energy always useful? (à loss of E into less useful E)
● Energy is always conserved, because energy can not be created nor destroyed.
Some forms of energy are more useful than others. For example, electrical energy is
very useful, while low temperature thermal energy is quite useless.
What makes a system more efficient?
● Reducing the number of useless inputs and replacing them with important inputs to
get out more useful outputs.
Why are most systems not 100% efficient?
● Energy is lost as waste in the form of heat, sound or other forms
○ They can be lost due to factors such as friction, resistance etc.
, What is the most common wasted form of energy?
● Thermal energy, specifically in the form of heat
○ Friction creates heat
○ Combustion creates heat
○ Etc.
Why does matter and energy disperse?
● Matter and energy disperse due to the second law of thermodynamics, which states
that systems tend to increase in disorder. Random particle motion and interactions
result in natural spreading and dispersion over time.
How does heat get conducted?
● Heat conduction is a process by which heat is transferred from one object to
another through direct contact
● Heat flows from the hotter object to the cooler object
● It occurs because atoms in the hot object are moving rapidly and collide with each
other
● When they collide with other atoms or molecules in the cooler object they transfer
some of their energy, which we perceive as heat
How does heat get convected? Why are solids not able to convect heat?
● Convected means that heat is transferred by the movement of a fluid such as a
liquid or gas
● How does this process happen:
○ Heating - the fluid is in contact with the heat source and the fluid warms up.
This causes the fluid particles to gain energy and move faster becoming less
dense
○ The less dense heated fluid rises to the top and the cooler, denser fluid,
descends. This creates a convection current. The rising hot fluid carries the
heat away from the heat source
○ The heat is then transferred to cooler areas
● Solids aren’t able to convect heat, because the substance needs to be free to move.
Why do objects in the same room feel that they are at different temperatures?
● Because some objects conduct heat better than others
● For example metal feels cool because it conducts the heat away quickly and easily
What happens in an ecosystem in terms of MATTER and ENERGY?
● Energy moves through an ecosystem, it changes form, but no new energy is created
● Similarly, as matter cycles within an ecosystem, atoms are rearranged into various
molecules, but no new matter is created.
● Matter and energy are conserved
What does Energy allow us to do?
● Energy allow us to do work and accomplish tasks, e.g.:
○ Move
○ Perform physical activities
○ Generate heat and light
○ Etc.
How does Energy manifest itself?
● Energy exists in different forms:
○ Mechanical energy (motion of objects - kinetic and potential energy)
○ Thermal energy (heat)
○ Chemical energy (energy stored in the bonds between atoms and molecules)
○ Electrical energy (energy associated with the movement of electric charges -
wires)
○ Radiant energy (microwaves)
Is Energy always conserved? Is Energy always useful? (à loss of E into less useful E)
● Energy is always conserved, because energy can not be created nor destroyed.
Some forms of energy are more useful than others. For example, electrical energy is
very useful, while low temperature thermal energy is quite useless.
What makes a system more efficient?
● Reducing the number of useless inputs and replacing them with important inputs to
get out more useful outputs.
Why are most systems not 100% efficient?
● Energy is lost as waste in the form of heat, sound or other forms
○ They can be lost due to factors such as friction, resistance etc.
, What is the most common wasted form of energy?
● Thermal energy, specifically in the form of heat
○ Friction creates heat
○ Combustion creates heat
○ Etc.
Why does matter and energy disperse?
● Matter and energy disperse due to the second law of thermodynamics, which states
that systems tend to increase in disorder. Random particle motion and interactions
result in natural spreading and dispersion over time.
How does heat get conducted?
● Heat conduction is a process by which heat is transferred from one object to
another through direct contact
● Heat flows from the hotter object to the cooler object
● It occurs because atoms in the hot object are moving rapidly and collide with each
other
● When they collide with other atoms or molecules in the cooler object they transfer
some of their energy, which we perceive as heat
How does heat get convected? Why are solids not able to convect heat?
● Convected means that heat is transferred by the movement of a fluid such as a
liquid or gas
● How does this process happen:
○ Heating - the fluid is in contact with the heat source and the fluid warms up.
This causes the fluid particles to gain energy and move faster becoming less
dense
○ The less dense heated fluid rises to the top and the cooler, denser fluid,
descends. This creates a convection current. The rising hot fluid carries the
heat away from the heat source
○ The heat is then transferred to cooler areas
● Solids aren’t able to convect heat, because the substance needs to be free to move.
Why do objects in the same room feel that they are at different temperatures?
● Because some objects conduct heat better than others
● For example metal feels cool because it conducts the heat away quickly and easily
