Recent content by scerab

Would anyone help me understand how did the ancient Greeks managed to calculate the earth’s circumference using knowledge of the angle of elevation of the Sun. I wonder if they had any means of magnification such as lens. They did make some pretty accurate conclusions for the limited technology...

I know that heat increases the velocity in which the atoms move with in a solid substance that leads to farther expansion, and cooling does the opposite. My question how ever is this: will an alloy or metallic substance (say Iron) crack or break via accelerated heating then rapid cooling...