Which was Charles Darwin’s contribution to the study of biology? He was the first person to recognize that organisms change over time.
He believed that organisms adapted through the inheritance of acquired traits.
He explained how traits are passed from parents to offspring.
He proposed that natural selection is the primary mechanism of evolution.

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