What might be a symptom of a person whose vein valves are not functioning properly and are causing fluid to flow away from the heart?

Ihaven't done that yet, so no idea,but this is not the right place to ask

What subject are you on

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