Swing and Sand! Why Do Some Clocks Use Swings or Sand?

What Crafty Clover says in this video

Intro

Hi! I'm Crafty Clover! Let's discover something amazing. Why do some clocks use swings or sand?

The Big Idea

Anything that repeats in a steady way can be a clock! A swinging weight repeats. So does sand trickling down. People used these repeaters for hundreds of years, long before batteries.

Step 1

Step 1: pick a repeating move. A pendulum is a weight hanging from a string, and it swings back and forth. Each swing takes almost exactly the same time!

Step 2

Step 2: make it steady, and count the repeats. Clockmakers keep the string the same length, because a longer string swings more slowly. Then they count the swings, and turn the count into seconds.

Step 3

Step 3: reset and go again. An hourglass lets sand fall through a tiny hole, at a steady rate. When the top is empty, flip it over, and it counts again.

A Closer Look

Here are two old clocks. The pendulum swings back and forth. The hourglass drips sand from top to bottom. Each one counts by repeating, again and again.

Quick Facts

Quick facts! Before batteries, gravity was the engine of many clocks. The Italian scientist Galileo studied swinging weights more than 400 years ago. Today, tiny vibrating crystals and atoms count even more finely. Sundials use the Sun's shadow to tell time.

Think Like a Scientist

Now, think like a scientist! Ask: what must stay the same for a swing to be a fair clock? And ask: why do we reset the sand? Try it at home: tie a small weight to a string. Swing it, and count 10 swings. Then try a shorter string!

Outro

A swing or a trickle of sand can count time, if it repeats steadily! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!