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Tell the time with your own water clock

Science Projects - Earth Science and Astronomy

Suitable For

Grade 3

Difficulty

2

Time Required

 <12 Hours

Supervision

Advised

What’s it about?

Since ancient times people needed to be able to tell time. These days, we use digital wrist watches or electric clocks to accurately tell the time, but in the old days telling time was not such a convenient task. They used hourglasses, candle clocks and a device called a water clock.

Do the following science experiment to learn how water can be used to tell time:

Topics covered

Galileo Galilei

What will I need?

  • MARKING PEN
  • STOP WATCH
  • SMALL NAIL
  • BOOKS
  • TAP WATER
  • 2x TRANSPARENT PLASTIC CONTAINERS
  • STICKY TAPE

Procedure (Method)

Since ancient times people needed to be able to tell time. These days, we use digital wrist watches or electric clocks to accurately tell the time, but in the old days telling time was not such a convenient task. They used hourglasses, candle clocks and a device called a water clock. Do the following science experiment to learn how water can be used to tell time:

Science project diagram
  1. Make two plastic containers by asking an adult helper to cut in half two 1L plastic water bottles, so that you have two large transparent plastic ‘cups’
  2. Use a thin nail to make a small hole in the centre of the bottom of one of these containers. Place a piece of sticky tape over the hole and fill this container with some water.
  3. Build a ‘stand’ out of books or similar objects so that the empty container fits in below the container with the water and the hole.
  4. With the configuration as above, quickly remove the piece of tape and ask a friend to start the stop watch at the same time to start timing the water dripping from the hole in the top container to the bottom container.
  5. After 1 minute, use the magic marker to mark the ‘1 minute’ water level on the bottom container. Keep on marking the water levels at one minute intervals until all the water has dripped into the bottom container.
  6. Tape the hole, and refill the top container with the water from the bottom container. Set up as before and remove the tape. This time you do not need the stop watch, as you now have a ‘water clock’ that tells the time in minutes!

How does it work?

In the above science experiment we have built a timing device or ‘water clock’. This works because of the fact that liquids or water flows out of the small hole in the bottom of the container at a constant rate. All timing devices, even digital watches, use the same fundamental principle that a regular pattern or cycle operates at a constant rate.

In this experiment, the drops of water occur at a known rate allowing us to tell the time. Similarly, the constant swing of a pendulum in a grandfather clock is used to tell the time, or the regular vibrations of a quartz molecule are the basis of a digital watch. The earth’s rotation around the sun is also used to tell time and is how the seasons and years are determined!

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