Potential and kinetic energy
Potential and kinetic energy, energy conversion, efficiency and power. Read one part at a time and tap “I know this”. Then test yourself in the quiz.
Know it already? Jump straight to the quiz
Stored and moving
| Potential energy (stored) | Kinetic energy (movement) |
|---|---|
| A book on a high shelf | A ball flying through the air |
| A stretched spring (elastic) | Water falling through a turbine |
| Food (chemical) | A moving car |
Conversions
| Device | Conversion |
|---|---|
| Light bulb | Electrical → light and heat |
| Loudspeaker | Electrical → sound |
| Car engine | Chemical → kinetic and heat |
| Plant | Light → chemical |
| Dam water through a turbine | Potential → kinetic → electrical |
| Rubbing hands | Kinetic → heat |
The total stays the same (conservation of energy); what seems ‘lost’ mostly becomes heat.
Save electricity
- Heating uses much more energy than light or sound.
- Switch off the geyser’s heating when not needed: the biggest saving.
- A TV and charger left on standby all day waste electricity.
- A device is more efficient when less energy is lost as heat.
Remember this and test yourself
- Potential energy is stored (a book on a high shelf); kinetic energy is movement (a ball in the air).
- A falling stone: potential → kinetic. A pendulum: most kinetic at the bottom, most potential at the top.
- Energy is measured in joules; power (energy per second) in watts.
- No appliance is 100% efficient: some always escapes as heat.
- Appliances that make heat use the most electricity; switch off the geyser when it is not needed.
Write these points in your book. Read them again the night before the test.
Potential = Parked at the top of the hill. Kinetic = Kart racing down. On the way down they swap, but the total stays the same.
Important words
First say what the word means, then turn the card over.
Match column A to column B
Tap a word in column A, then its meaning in column B. You can also start in column B.
True or false?
Read the question and the answer. Is the answer right? Tap True or False.
Now the real quiz!
The quiz has many more questions on this topic. Every question shows straight away whether you are right and explains why.
Take the quiz: Potential and kinetic energy- Read one part together and ask your child to tell it back in their own words.
- The ticks (“I know this”) are saved on this device only. We never ask for names or emails.
Follows CAPS for Grade 7 Natural Sciences. Always check your teacher’s notes and textbook too.