D.I.Y project – How to make a bouncy ball

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Using science, create your own bouncy ball! Test its ability to bounce against the bounce of other balls you have – and most importantly, have fun

You will need:

  • Borax (found in the laundry section)*
  • warm water
  • cornflour
  • glue
  • 2 small mixing cups
  • a stirring stick (plastic spoon)
  • food colouring (optional)

*children should wear gloves and be supervised by an adult

 

Method:

  1. Label one cup ‘Borax Solution’ and the other cup ‘Ball Mixture’.
  2. Pour 4 ounces of warm water into the cup labelled ‘Borax Solution’ and 1 teaspoon of the borax powder into the cup. Stir the mixture to dissolve the borax.
  3. Pour 1 tablespoon of glue into the cup labelled ‘Ball Mixture’. Add 3-4 drops of food colouring, if desired.
  4. Add 1/2 teaspoon of the borax solution you just made and 1 tablespoon of cornflour to the glue. Do not stir.
  5. Allow the ingredients to interact on their own for 10-15 seconds and then stir them together to fully mix.
  6. Once the mixture becomes impossible to stir, take it out of the cup and start moulding the ball with your hands. The ball will start out sticky and messy, but will solidify as you knead it. Once the ball is less sticky, continue rolling between your hands until it is smooth and round!

 

What’s the Science?

 

This activity demonstrates an interesting chemical reaction, primarily between the borax and the glue. The borax acts as a “cross-linker” to the polymer molecules in the glue – basically it creates chains of molecules that stay together when you pick them up. The cornflour helps to bind the molecules together so that they hold their shape better.

 

Time to Experiment!  

 

  • Try adjusting the amount of borax, glue, and cornflour to see which combination results in the highest bounce.
  • Make one batch with clear glue and one with white glue. How does this affect the appearance of the ball?
  • Discover the best way to get the bouncy ball to keep its bounce over time.
  • Does the ball bounce better on the carpet or a wooden floor? Experiment with other surfaces.

 

bounce

 

 

 

 

 

 

 

 

 

 

 

Image source: Bravia