New Scientist - USA (2020-08-22)

New Scientist Books Why do boys have nipples?

HOW TO MEASURE

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Sound is very slow compared with

light. That provides a very low-tech

way to measure it, given the right

outdoor space.

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• a hammer


• a grown-up helper capable of

safely wielding the hammer

• a hammer-resistant and preferably

resonant surface (a wall, piece of

metal or rock will do)

• a stopwatch

(or a clock with a second hand)

• a very long measuring tape or

a measured ball of string

• a pair of binoculars


• a very large garden or flat open

space such as a beach or a park

(Add a metal coat hanger, some s

tring and a spoon to check out further

properties of sound.)

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out by an adult because a hammer is used.

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once every second with the hammer – they’ll need

to use the stopwatch and maintain a regular beat.

Begin walking away from your helper, looking back

from time to time. When you are a few hundred

metres apart, use the binoculars if necessary.

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As the distance between you and your helper

increases, the delay between them striking the

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become greater. Eventually, the delay will match

the time between each beat and the sound will

once more appear to coincide with the action of

the hammer.

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