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LAW OF CONSERVATION of
ENERGY
In the golf ball investigation, can we account for all the energy in the system? Basically, if we add up all the PE, KE and any friction, will it equal the total energy (TE) in the system?
Yes, scientific evidence leads us to believe that ALL of the energy in any example can be accounted for! But it is not always easy in an open system.
LAW OF CONSERVATION of ENERGY
Energy cannot be created or destroyed; it can only be transformed or transferred.
Total Energy is all the energy in a systemThe TOTAL ENERGY (TE) will always stays the same!!!
TE = PE + KE + heat
LAW OF CONSERVATION of ENERGY
The TOTAL ENERGY of a system can be measured by adding PE + KE + Heat.
TE = KE + PE + heat
Q: Where does the heat come from???
A: Friction!!! (Rub your hands together and see what happens!!!)
LAW OF CONSERVATION of ENERGY
TE will equal the GPE at the highest point in a system!
TE=GPE at the highest point
100 Joules of energy to start
100 Joules of energy at the end!
Equal at the mid point!“What you put in, is what
you get out!”(TE) NEVER CHANGES in a
system!
A
B
C
LAW OF CONSERVATION of ENERGY
Let’s look at the pendulum swing. Will it continue to swing with same amount of energy over time?Why won’t the beginning energy ever equal the end energy???
Hint: Can heat be contained in an open system?
NO… please remember that energy is not destroyed, but some of it can escape from the system to the surroundings in the form of heat from the rope.
LAW OF CONSERVATION of ENERGY
This is why no system will ever be 100% efficient… Meaning the beginning energy will never equal the end energy…There is no such thing as a frictionless system!!!
2. In an energy chain, only KE and GPE are to be included.AGREE DISAGREE
As energy is transferred and transformed in a system, some of the energy is lost.
AGREE DISAGREE
Work is the same thing as energy.AGREE DISAGREE
If something has a lot of energy, it also has a lot of power.AGREE DISAGREE
ENERGY CHAINSSince energy is transferred and transformed all the time, it is helpful to be able to track the “flow” of energy in systems.
A map of what happens to energy, where it goes, and how it changes is called an Energy Chain.
Energy chains can be created using words, pictures, arrows, or any combination of things that show the movement of energy in an example.
Energy ChainsCan you think of how the energy
flows through a car? What would you start with? What types of energy
transformations are happening?
Energy Transfer and Transformation
Chemical
Electrical
ThermalMechanical
Kinetic Energy
Thermal Energy
Can you construct an Energy Chain for a person hitting a
softball to the outfield?
