density experiment

[bknewsed]

How can I make something float, sink, then float again, without touching it

[Clanad]

Alternately heat and cool the water...

[gen2]

If the object contains air pockets, you could also do it by reducing / increasing the air pressure.

[plowter]

How about this submersible robot change its buoyancy?

[delboy3]

Pull the chain

[MatydaLover]

I have a thermometer that has little glass balloons that rise and fall according to the temerature. Great fun working out why it works.

[north star]

Change the density of the liquid the object is floating / immersed in. Parafin / Kerosene for example instead of water.

[35Flipper]

I seem to remember dropping a peanut in lemonade when I was younger and it did exactly that...

[Ice.Maiden]

I'm sorry bknewsed - I was trying to give you a sensible answer, and then read delboy's reply. Fall about laughing.