What is the eccentricity of a completely flat ellipse?

Eccentricity is a measure of how 'out of round' an ellipse is.  If the eccentricity is zero, it is not squashed at all and so remains a circle. If it is 1, it is completely squashed and looks like a line. Hope this helps. Have a nice day. Feel free to ask more questions.

Because the carnivores keep the herbivore population in check 

It depends on the surface of the levels. the rougher the surface, the greater is the frictional force. for rougher surfaces, you would need to exert greater force to move the object. the concept is that, you must overcome the frictional force in order to bring the object into motion. this is the reason why we add lubricants to the joints so they could easily move. this answer was on