How do you expect /k to depend on the size of the contact area between the two sliding surface ? O uk is inversely proportional to size of the contact area between the two sliding surfaces O All of the above O uk is independent of the size of the contact area between the two sliding surfaces O uk is directly proportional to size of the contact area between the two sliding surfaces O None of the above QUESTION 3 How do you expect the coefficient of friction to depend on the normal force? For example, do you expect uk to increase, decrease, or remain constant as the normal force is increased? O uk is directly proportional to the normal force O All of the above O uk is independent of the normal force None of the above O uk is inversely proportional to the normal force