To test a new drug that has the potential of curing people of the common cold, a company asked human volunteers who were coughing and sneezing

to participate in a clinical study. The objective of the experiment was to test

whether the new drug could cure the volunteers in the experimental group of

the common cold.

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