Q.

what is a cork?

a.

it is the outer covering of a tree.

is this answer correct?

I don't think it's the best answer you could say that it's a living organism that you can find on the outer covering of a tree.

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