What was copernicus’ hypothesis and why was it so controversial

This model positioned the Sun at the center of the Universe, motionless, with Earth and the other planets orbiting around it in circular paths, modified by epicycles, and at uniform speeds.

Explanation:

ww1 weapons: tank. tanks were used for the first time in the first world war at the battle of the somme. they were developed to cope with the conditions on the western front. the first tank was called 'little willie' and needed a crew of 3.