Did you ever experience a shove when the car you were travelling in suddenly took a turn? Or have you ever wondered why water does not spill out of a bucket that is being swung around? The reason for both these occurrences is the same. Here’s a very simple activity that I include in the homeschool curriculum that I teach.
The Swirling Can Experiment: Tie a string to an empty soup can in such a way that you can hold some water in the soup can while suspending the can from the string. Fill the can partly with water and, holding the string, swirl it around in a horizontal loop by placing your hand above your head. Now swirl it around in front of you making a vertical loop. Does the water spill while the can is in motion? Why not?
The Answer: If you swirl the can at a particular speed the water will not spill out. As you swirl the can faster the water will feel heavier and press against the bottom of the can. The faster you swirl the heavier will the water feel and the harder it will press towards the bottom of the can. As the can is swirled, the water actually wants to travel in a straight line, but the can turns and obstructs the water, maintaining contact with the water. Therefore the water is not thrown out of the can.
The English scientist, Sir Isaac Newton, explained this phenomenon centuries ago. He said that an object moving in a straight line would continue moving in a straight line unless an external force acts on it. So as your car changes direction, your shoulders and head continue in a straight line even though your car has changed direction. The door hits you and changes the direction of your upper body to the same direction of the recently swerved car. This is an example everyone experiences in practical life, and therefore makes a great homeschool curriculum topic.
This change that the water in the can or your body feels while travelling in your car is called the G-force. G-force is measured by units such as 0 g, 1 g, 2 g, 3 g, and so on. If you are experiencing 0 g, it means that you are experiencing weightlessness, as astronauts experience when their spacecrafts leave the gravitational field of the earth. A G-force of 1 g means that you will feel your normal weight. A G-force of 2 g means that you will feel twice your weight, and so on. Now we will build an accelerometer in order to measure G-force. This is another activity that I always include in the homeschool curriculum that I teach.
Homemade Accelerometer: Make a ring with a transparent flexible pipe and connect both the free ends with a union or a connector. Fill the pipe with colored water till it is half full before attaching the union. Now place the ring on your table and mark the 3 o’clock and 9’oclock positions while the union is at the 6 o’clock position. Now write 1 g at the 10:30 position and 2 g at the 11:15 position.
Let me explain the number game. If the hands of a clock are at the 9 o’clock position, there is an angle of 90 degrees between the hands. When the angle is reduced to half, that is 45 degree, the small hand will be at 10:30: the 1 g mark. Still half of 45 is 22.5 degrees, that at 11:15- the 2 g mark. Can you guess where the 3 g mark will be? Now it’s time to measure the G-force you experience in your car. Grasp the accelerometer ring at the 3 o’clock mark and measure how high the colored water rises when your car swerves. You can also measure the G-force while sitting on a rotating office chair.
If you enjoyed your swirling can and accelerometer experiment, I want to tell you that I have many such exciting activities for you. Click the link below for your free “Homeschool Parent’s Guide to Teaching Science”, filled with great science experiments and activities.