- Old bed sheet or towels
- Large baking pan or shallow cardboard box
- Flour (enough to fill the pan)
- Cocoa powder (enough to create a thin layer on top of the flour)
- Sieve or sifter
- Balls of various sizes
- Optional: ruler or metre stick
- This project is messy! Before you begin, lay down a sheet or towels to make clean-up easier.
- Fill the baking pan with flour.
- Use the sieve to put a thin layer of cocoa powder on top of the flour.
- Try dropping a ball into the pan from about half a metre above it (if you have a metre stick, use it to drop the ball from a consistent height).
- Look at the resulting impact crater. What colour is the surface immediately around the crater? How does that compare to the surface of the rest of the pan? How far did the flour and cocoa powder spread?
- Try dropping the same ball from a different height. What does the resulting crater look like?
- Try dropping balls of different sizes from the same height, and examine the resulting craters.
- You can even try throwing a ball sideways so it hits the pan at an angle, instead of coming straight down. How is the resulting impact pattern different from when you dropped the balls straight down?
- If needed, smooth out the surface of the pan, and sift a fresh layer of cocoa powder on top.
You should have found that the bigger the ball, or the faster it was moving, the bigger the resulting crater would be. This is because larger, faster-moving balls have more kinetic energy than smaller, slower-moving balls. This energy is transferred to the flour and cocoa powder when the ball hits the ground, causing it to fly outward, creating the crater (and a mess!).
In addition, you should have seen that the impacts churned up the "soil," bringing some of the white flour to the surface near the impact site. While the pattern around the crater was probably symmetric if you dropped the ball straight down, sideways impacts would result in asymmetric patterns as more flour/cocoa powder were thrown in one direction than the other.
This activity was inspired by the Institute for Earth and Space Exploration, Western University and Science Buddies.