Giraffes have long necks that allow them to eat leaves in trees. what characteristic of life is this most directly an example of?

I would say the characteristic of adaptation 

The answer would be a. aluminum can

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