Rocket ties a metal washer to a string. He hangs it from his finger and lets it go.
The washer swings out and back, out and back. "It is a tiny playground swing!" Rocket says.
Raven leans close. "What do you notice? Does each swing take the same time?"
Nova blinks. "Count the swings while someone counts the seconds," she says.
A pendulum is a weight that hangs from a string or rod. It swings back and forth.
Gravity pulls the weight down, so it swings back toward the middle.
One swing means the weight goes out and comes back to where it started.
Scientists count swings to find the pattern.
Here is a practice table. These numbers are made up for practice. They are not from a real test.
| Practice table (made-up numbers) | Swings in 15 seconds |
|---|---|
| Try 1 | 10 |
| Try 2 | 10 |
| Try 3 | 10 |
Scientists count swings in a set amount of time, like 15 seconds.
They try it more than once. If the count repeats, they trust the pattern.
If one try is very different, they look for a mistake. Maybe someone counted wrong.
| Statement | True or false? |
|---|---|
| A pendulum is a weight hanging from a string or rod. | ? |
| Gravity pulls a pendulum weight back toward the middle. | ? |
| One swing means the weight goes out and does not come back. | ? |
| Scientists try a test more than once. | ? |
Well done! Tomorrow you build your own pendulum and count real swings.