|
 |
|
|
|
Why not have a go at making your own clock with a piece of string. It sounds ridiculous but it is possible and it does work! |
|
|
|
|
|
Start by taking a piece of string. It needs to be just over one metre in length. |
|
|
|
|
|
You will also need a weight. It can be a few hundred grammes heavy but it must be small. A key or nut is perfect. Tie it to one end of the string. |
|
|
|
|
|
Secure whatever weight you choose by tying a double knot. |
|
|
|
|
|
Tie the other end of the string onto a ruler like this. The string must be exactly 101.5cm from the ruler to the weight. This is critical - if it's not that length, the clock won't work! |
|
|
|
|
|
Now hold the ruler steady, over something sturdy. Hold the string to one side and make sure it's taut before releasing. |
|
|
|
|
|
You can release the string from any angle, but whichever one you choose you must be careful not to push it when you release. |
|
|
|
|
|
What you'll have is a pendulum - the mechanism used in old clocks. Gravity - the force of the earth which makes thing fall - makes the pendulum swing. |
|
|
|
|
|
If you give it a go, compare the number of swings with time. You should get one swing per second. |
|
|
|
|