A Water Clock

What you need:

  • An empty one-litre mineral water bottle,
  • a pin,
  • a watch,
  • measuring tape,
  • a marker
  • and some water.

What you do:

  • Make a small hole close to the bottom of the empty bottle with the help of a pin.
  • Mark the bottom of the neck with a marker. Measure the length of the bottle, from the hole to the bottom of its neck and mark the midway point.
  • Cover the hole with your finger and fill the bottle with water, up to its neck.
  • Note down the time on your watch and then release your finger from the hole. Observe the water flowing out.

Now calculate:

A. The time taken for the water to flow from the bottom of the neck to the mid point.

B. The time taken for the water to drip from the mid point to when it stops dripping completely.

C. The total time taken for the water to drip out completely. Suppose it takes a full hour, you have a ‘one hour’ water clock. If it takes 50 minutes, you have a ’50 minutes water clock.

Compare Your Findings:

C= A +B

is A=B?

Did the water drip out at a constant speed?

Can you say that the water clock shows accurate time? Find out.