You are wondering how fast you can drive your bike but not get your feet wet when the road is full of water?(adsbygoogle = window.adsbygoogle || []).push({});

The answer is simple: about 2.5m/s (meters per second) or roughly 9km/h (kilometers per hour), or 5.6mph. See below for the demonstation:

This is a simple physics problem which is solved using the law of conservation of energy. The more interesting fact is that your speed will not depend at all on the mass of the water drop that flies off the spinning wheel. The key to the solution is considering that the drop will fly off with the speed of your wheel which is, in fact, the speed indicated by your speedometer. So, in your reference frame the drop flies from zero ground when it has maximum velocity to, say 30cm when it has no velocity at all. This means that the mass of the droplet x(multiplied by) height 30cm x gravitational constant(approx 10) must equal the mass of the droplet (again!) multiplied by the square of the velocity over two. This law states that the potential energy must equal the kinetic energy of the drop, and more, that the initial kinetic energy of the droplet transforms into the potential energy at the level of your feet. Dividing each sides of the equation by the mass of the droplet we obtain that the velocity does not depend on this mass. So, there you have it: v=square root of 2*10*height which yields about 2.5m/s. So we learn from elementary physics that you must not drive faster than this speed if you don't want to get wet:)

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# How fast you can drive your bike but not get wet?

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