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♻️ Energy Can't Be Created or Destroyed

Explore one of science's biggest rules: energy is never made or lost, only moved and changed. Follow it through roller coasters, dams, and braking cars.

lessons

~15 min

to learn

🔬 Science

subject

Ages 6–12

level

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What you’ll learn

The Great RuleState the law of conservation of energy: energy cannot be created or destroyed.Energy makes everything happen, yet the total amount never changes. The conservation of energy says energy cannot be created from nothing or destroyed; it can only be transferred or changed in form. This is why no machine can give out energy without first being given energy.
Energy TransformsGive examples of energy changing form while the total is conserved.Energy constantly changes form: chemical energy becomes movement, electrical energy becomes light and heat, and stored energy of height becomes motion on a roller coaster or at a dam. Through every change, the total energy is kept the same.
Where Does It Go?Explain that energy which seems lost has spread out, mostly as heat, with the total unchanged.When things slow down, their energy seems to vanish, but it has spread into the surroundings, mostly as heat from friction. A braking car's motion becomes heat in the brakes and a little sound. Add every bit up and the total energy is exactly what it was before.

Questions this course answers

What does the conservation of energy say?

Energy can never be created or destroyed; it can only be transferred or changed in form.

Why can no machine make energy from nothing?

Energy cannot be created, so any machine must first be given energy before it can give energy out.

On a roller coaster, the stored energy of height mainly changes into what as it drops?

As the coaster falls, its stored energy of height changes into energy of motion, speeding it up.

What energy change does a loudspeaker make?

A loudspeaker turns electrical energy into sound energy.

When a moving car brakes and stops, where does its energy of motion mostly go?

Friction in the brakes turns the car's energy of motion mostly into heat, so the brakes get hot.

When energy spreads out as heat and sound, what happens to the total amount?

The total energy stays exactly the same; it has only spread out and become harder to use.

Grounded in trusted sources

BBC Bitesize
The Physics Classroom
Britannica

Every Wunder lesson is built from real, reputable sources — never invented.

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