How to make a project on the size of the earth?

Answer 1

The easiest way that a science project on a shoestring budget can even hope to guess the size of the earth is to first assume it's round, and then either

1) From a high place like a skyscraper or a mountain, make an estimate how far the horizon appears to you, or

2) From the ground, make an estimate how far away you can still see an object before it disappears below the horizon

You have 2 variables, the distance D and the height H. The diameter of the Earth is D^2 / H. (Figure out why this should be, it's a math problem).

Much care has to be taken to ensure accurate D and H, maps will be needed, and you need flat land or water for this to work. In example 1), H is the height of the building or mountain, D is the distance to the horizon, which can be determined by spotting small objects almost before they disappear in the distance. In example 2), H is the height of the object (like a ship) that just disappears below the horizon, and D is the distance to it from you.

Answer 2

First become God. The rest will be easy. Othewise, forget it.
Why are you asking a question like this.

Answer 3

longharia and Mitchell W have the answer. I cannot define it more clearly.

Answer 4

you can work on it out of the space.