Editor's note: This article was originally published in the Sep/Oct 2012 issue of Home School Enrichment Magazine. Learn more at www.HomeSchoolEnrichment.com

Ancient Greece had many well-known mathematicians, philosophers, and scientists. Therefore, many discoveries happened in this part of the world during that ancient time period. 

Although most people of Ancient Greece did not even know of the One True God, He had equipped them with the ability to think and create. Euclid, a famous mathematician, first wrote the basic rules of geometry. Pythagoras, another Greek mathematician, created the Pythagorean Theorem, which states that a2 + b2 = c2. Both of these men’s works are still used today. How can such things be discovered by people who did not even know of God? Because the order that God created when He made the world can be observed by anyone. Even people who don’t know Him can discover His truth about the world around them.

Another famous inventor from the time of Ancient Greece was Archimedes. Archimedes had an incredible ability to discover how to make things happen based on the laws set by God within creation.

Give It a Try #1: The Law of Displacement

There is a famous story about Archimedes discovering that the king’s crown was made incorrectly by using the law of displacement. My children and I enjoy listening to this story as told by Jim Weiss on his Galileo and the Stargazers audio CD. What is the law of displacement? Let’s “Give It a Try” and find out.

Items Needed:

  • One clear container (if you use a graduated cylinder or measuring cup with “mL” marked on it, you will be able to calculate the volume displaced)
  • Water
  • Three similar-sized objects such as marbles, pebbles, etc.
  • Masking tape (if you do not have a measured container)
  • A small scale that measures grams (this is optional—only needed if calculating density)

Directions:

Pour the water into the container, filling it about half-full. If you do not have a measured container, place a piece of tape on the side of the container at the height of the water level. If you are using a measured container, record the height of the water.

Carefully, without spilling any water, place one of the objects into the water. Now observe the water level. Has there been any change? Record it. Add another object to the water. What did this object do to the water level? Once again, record the change. Place the third object into the water and record any changes seen.

Now, think about what happened. What do you think displacement means based on this experiment? What happened to the water? Did you know that the definition of displace is to move or shift from the usual position? Isn’t that what happened to the water in the experiment? The Law of Displacement, which is also called the Archimedes Principle, states that an object immersed in a fluid (like water) is subject to an upward force (buoyancy) equal in magnitude to the weight of the fluid that it displaces. So basically, the water moved or was displaced because of the mass of the object put into it.

If you would like to calculate this further, weigh one of the objects you placed into the water to find its mass. (Technically, weight and mass aren’t the same thing, since mass is inherent to an object while weight is a force and depends on gravitational pull; that’s why things weigh less on the moon. However, since we’re doing these experiments on Earth, we can use the object’s weight as its mass.)

Density = Mass ÷ Volume (of the fluid displaced by one object). For example, if your marble weighed 2 g and it displaced 5 mL when it was placed into the water, you can get the density by dividing 2 g by 5 mL. Therefore, the density is 0.4 g/mL3 (0.4 grams per cubic milliliter).