Does a bigger ball make a bigger crater?
The question
When we drop balls of different sizes into flour, which makes the biggest crater?
Craters on the Moon and Earth were made by space rocks crashing into the ground. Bigger, heavier rocks make bigger craters.
Equipment
- A deep baking tray of plain flour, with a sprinkle of cocoa powder on top
- Three balls of different sizes, such as a marble, a ping-pong ball filled with sand (taped shut) and a tennis ball
- A ruler
- A sheet or newspaper under the tray
Method
- Smooth the flour flat and sprinkle cocoa on top.
- Hold the smallest ball at the same height each time, about as high as your shoulder when kneeling, and let it go. Do not throw it.
- Lift the ball out carefully and measure across the crater with the ruler.
- Smooth the flour again and repeat with the other balls.
- What to measure
- How wide each crater is, in centimetres, and how far the white flour was splashed over the brown cocoa.
- How to present it
- Draw or photograph each crater next to its ball, with the width written underneath, and line them up from smallest to biggest.
- Take it further
- Drop the same ball from different heights and see if the crater changes. Look at a picture of the Moon and find craters with bright splashes around them.
Safety
Drop, never throw. Nobody eats the flour, and anyone with a flour allergy uses sand instead. Sweep up spills so no one slips.