What it shows
Air rushing backwards out of the balloon pushes the car forwards. This is Newton’s third law: every action has an equal and opposite reaction.
This idea has a short entry only. For the science behind it, read the sentence above with your textbook and ask your teacher to explain the law or idea it shows, so you can describe it in your own words.
Materials
- A balloon and a drinking straw
- A plastic bottle or stiff cardboard for the body
- Four bottle caps for wheels
- Two wooden skewers or straws for axles
- Tape and glue
Safety
This project uses safe, everyday materials. Still, read the rules below with a parent before you start.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
All the safety rulesHow to go about it
Numbered steps have not been written for this idea yet. Plan it with your teacher: sketch the design with measurements, build one part at a time, test each part, and write every observation with the date. The free ebooks below have step-by-step projects of the same kind.
Take it further
Try a bigger balloon or a wider straw, and measure how far the car travels each time.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
Free ebooks for this project
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