On 01/06/2010 17:00, Tim Watts wrote:
On 01/06/10 16:46, Bob Eager wrote:
On Tue, 01 Jun 2010 01:47:11 -0700, Matty F wrote:

I wish to make a large Newton's Cradle. That usually consists of five
suspended steel balls. Ideally the balls will be at least 2" in diameter
or up to 12" or 24" in diameter. If they were steel they are likely to
injure childen. So they can't be steel. Billiard balls bounce well but
are still too heavy. Golf balls don't seem to bounce properly so they
are no good, and are too small. Soccer balls don't bounce that well
either. Polystyrene foam is too flimsy.

Any brilliant ideas? I have an idea which I will experiment with.

Bowling balls?




Hang on a minute - this is Matty...

Can't you (OP) just get some solid blocks of stainless steel and turn
them into hollow spheres, obviously in 2 halves with a nice thread
around the diameter of each on so they screw into a perfect sphere?

Extra points for just using a file and angle grinder! ;-



I am of course referring to:

http://groups.google.co.uk/group/uk....d654d507?hl=en


Why do they have to be spheres? Any shape will do provided there's just
a point contact with each neighbour. Maybe it would even work if the
faces were flat surfaces, but the alignment would need to be perfect.

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