The Champions
Last week I was leading a one day workshop in Geneva. As we were taking the minibus back to our hotel I spotted (and photographed) the famous fountain. I say famous but there were several others in the bus who had never heard of it. I only know because of the opening sequence to one of my favourite childhood series, "The Champions". No one else seemed to remember this so I looked it up on youtube and there it is, the fountain in the background. The fountain is a good example of conservation on energy, KE at the bottom being converted to PE at the top, but how do you explain how the KE gets given to the water? The water isn't travelling that fast in the pipes. It's all to do with Pressure. The pressure in the pipe is made high by a pump, the pressure difference between the inside and out means there is an unbalanced force on the water which accelerates out of the pipe. It's all explained by Bernoulli's principle which states that for an ideal fluid, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy. So when the water comes out of the pipe the reduction in pressure leads to an increase in speed and as the water rise the increase in PE will result in a decrease in speed. Interestingly Bernoulli was Swiss, how appropriate.