- 1 hammer - something hard and resonant (and inanimate) to bang
it on - 1 clock with a second hand - 1 measuring tape - 1 helper
- 1 pair of binoculars Sound travels at 344 metres per second in
air at 20 °C. This is slow enough for noises to be noticeably
delayed when heard from even quite a short distance. You can use
this effect to measure the speed of sound. Ask your helper to a
hit a wall or a piece of metal repeatedly with the hammer, about
twice every second. The exact frequency of the beat doesn't
matter; it can be measured later. But the beat should be
regular. Now start walking away, looking back from time to time
to watch your helper pounding away as you listen to the sound of
their hammering. As the distance increases, the delay after each
beat before the sound arrives will become longer and longer.
Eventually the delay ... To continue reading this article,
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