GED Science
Energy Forms & Conservation
Energy is the ability to make things happen, and it wears different outfits — motion, height, heat, chemical, electrical. The iron rule is conservation: energy is never created or destroyed, only converted. Every question is really "trace where the energy went."
The words first
- kinetic energy
- energy of motion — faster or heavier = more
- potential energy
- stored energy — height, a stretched spring, chemical bonds
- conservation of energy
- total in = total out, always, no exceptions
- "lost" as heat
- not destroyed — converted to heat by friction, unusable but real
The method
THE OUTFITS
kinetic anything moving
potential raised, stretched, or compressed things
chemical food, fuel, batteries
thermal heat — where friction sends energy
electrical moving charge
radiant light
THE ROLLER COASTER (the classic)
top of hill: max potential, min kinetic
bottom of dip: max kinetic, min potential
every next hill is LOWER — friction converted some
energy to heat at every moment
TRACING A CHAIN
flashlight: chemical (battery) → electrical → light + heat
your bike: chemical (food) → kinetic → heat (brakes!)
Worked all the way through
The problem
A pendulum swings lower and lower until it stops. A student says the energy was destroyed. What actually happened?
- Step 1 — State the rule that forbids the student's answer.Conservation: energy cannot be destroyed, only converted.
- Step 2 — Find the converter.Air resistance and friction at the pivot act on every swing.
- Step 3 — Follow the energy.Each swing, friction converts a little motion energy into heat in the air and the pivot.
- Step 4 — Account for all of it.The pendulum's energy now exists as slightly warmer air and metal — spread out and unusable, but not destroyed.
On the board
rule: energy is never destroyed
friction + air resistance
the converters
kinetic → heat, every swing
swings shrink as energy leaks to heat
books balance: motion out = heat in
Answer
Friction converted the swing's energy into heat — converted, not destroyed
A second one, in a different form
Trace the energy: a hydroelectric dam lights a bulb in your kitchen.
water held high: potential
falls: potential → kinetic
spins turbine: kinetic → electrical
bulb: electrical → light + heat
Answer
Potential → kinetic → electrical → light and heat
The usual mistake
Starting the energy chain in the middle or running it backward.
Check yourself
If energy seems to vanish in a problem, hunt for friction — the missing amount became heat. An answer that creates or destroys energy is automatically wrong, no matter how reasonable the story sounds.
Practice it
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