A gold mine that allows highly acidic water to flow out of the mine into a nearby river,
killing aquatic life, is in violation of which
federal law?
A. The Superfund Act
B. Clean Air Act
C. Occupational Health and Safety Act

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