How can value affect visual weight ?

The stronger contrast in value between an object and the background, the more visual weight the object has. the stronger the contrast in value between an object and the background, the more visual weight the object has. dark values appear heavier than light values.

In design visual weight is the notion that design elements have varied weights that is some objects even on a two dimensional medium can appear to be heavier.

Answerthe third and fourth;

Studying history is very important so that we learn from past experiences and don't repeat the bad ideas/choices that might have been made. it can tell us how cultures conducted their lives and you can learn about interesting facts you might not know. hope this ! : )