Why do somethings sink and others swim? That’s a topic that makes for an interesting science fair project. Iron is a heavy metal and a small coin made out of iron will sink. Paradoxically a huge boat made out of iron manages to float well enough to cross vast oceans.So what makes this same metal act in such different ways? And more importantly how do we make this into a science project?

It is all a matter of displacement as Archimedes told us. Archimedes principle states that a body immersed in a fluid is buoyed up by a force equal to the weight of the displaced fluid.So as long as enough water gets displaced the object will float and if its does not then the object sinks.

Essentially this means that a certain diameter needs to be maintained for the object so that it will float. So we will make spherical shaped boats out of foil to check what the ideal diameter to float is. Now once the size is unable to push away enough water the boat will lose its buoyancy and sink.

So start from a specific size and then keep making larger sized boats out of foil till the largest one sinks. Then work backwards to see the smallest size that manages to float. Record all the data you generate. Take photographs for the display board and also ensure that you make some tables from the data that you have collected. It is a simple and interesting science fair project.