What is The second? — Physics

Definition 8.7 Primary & Middle School Physics · Chapter 8 — Measuring Time

The second is the unit of time used all over the world, written $\mathrm{s}$ . One second is about one calm heartbeat, or the steady tick of a big clock. Saying “one little crocodile, two little crocodiles” at a calm pace counts roughly one second per crocodile.

Two clocks: the short hand tells the hour. At half past three, it has walked halfway from the 3 toward the 4. — Two clocks: the short hand tells the hour. At half past three, it has walked halfway from the $3$ toward the $4$ .

Examples

Example 8.8 (Try it: how many seconds?)

Count seconds steadily while: you hold your breath comfortably; the tap fills a glass; a friend runs to the fence and back. The glass might take $6$ seconds, the run $20$ . Now the tooth-brushing and the song from before can get numbers — and numbers, as with lengths, can travel and be checked.

Example 8.9 (Hours on the clock)

Seconds are for short things. Long stretches are counted in hours: school mornings last hours, a night of sleep too. The clock’s short hand points to the hour: straight at the $3$ , it is three o’clock; between $3$ and $4$ with the long hand pointing straight down, it is half past three. A whole day and night together hold $24$ hours — while the Earth, remember, makes one full turn.

Read in context →

Examples

Related terms