10 March 2009

Testing the bounciness of balls

Having been hugely surprised by the bounciness of Quentin’s golf ball, today we tested the bounciness of some different balls.  What, we wondered, would be the properties of the bounciest.  What is it that makes a ball bounce high?

From an exciting selection of balls gleaned from the gym…..


each group chose 5 different balls.  These we poked and prodded to see what was the same about them and what was different.  Some were squishy and some were hard.  Some were big and some were small.  Some were heavy and some were light.  Some were orange and some were blue…..

We used what we had observed to predict which one of the five would be the bounciest.  Then we tested each ball, making sure that what we did was the same for each ball.  We needed to keep our tests fair.

We held each ball at the same level…..


before letting it drop to the ground.

Then we watched carefully to see how far it rose after the first bounce.  We marked the spot on our chart;


(from this photo you can see that ball number 2 bounced the highest).

Next, we used a metre stick to measure the height of each bounce;


(from this photo you can see that ball number 2 bounced up 55cm.)

Finally we constructed a table for our results and recorded the height of each bounce. 

So, what it is that makes a ball bouncy?  If you had to make the bounciest ball, what would you make it like?  Would it be squishy or hard?  Big or small?  Heavy or light?  Orange or blue?  Would it be like a tennis ball or like a golf ball?

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