Speedometer with sensors

Hey Forum,

I was wondering if someone could help me with my schoolproject. I want to see the speed on my longboard for example after 10 metres with a beginning speed of 10m/s. Like a sensor that tells my speed after a given distance and how long it takes to reach the sensor. I also would like to know if it is possible to make multiple sensors. I could find lots of guides on how to make a speedometer but not one that tells my speed for a specific distance.

Sorry for my bad english.

Thanks in advance

Sorry for the question: is a longboard a skateboard, a snowboard or something completely different? Do you expect the sensor to be on the board or in the environment? What accuracy is needed? The easiest way is probably to use a GPS system to get your speed. Tell us if you have other limitations.

You mean like two infrared beams across the path and measuring the time taken to cross the two beams?

Should be pretty easy to do once you find a suitable "beam break" sensor. (Hint: Google for that pair of words.)