The remora attaches itself to sharks by means of its –like mouth. it gets free transportation and protection and also the remnants of food material that escapes the shark's mouth. the shark does not benefit and is not harmed in any way by the remora. what kind of interaction do the remora and the shark demonstrate?
1. commensalism 2.parasitism 3. mutualism

Commensalism is the relationship between two organisms where one benefits from the other and the other is not affected in anyway. The interaction between the remora and the shark demonstrates this relationship.

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