Question

(a) When rebuilding an engine, a physics major must exert 3.00×102 N of force to insert a dry steel piston into a steel cylinder. What is the normal force between the piston and cylinder?

(b) What force would they have to exert if the steel parts were oiled?

Answer 1

The magnitude of the normal force between a dry steel piston and cylinder is 300 N, which is equal to the force needed to insert the piston. If the surfaces are oiled, less force is required due to lower friction, although the exact force depends on the coefficient of kinetic friction.

Step-by-step explanation:

(a) When a physics major is rebuilding a car engine and needs to exert a 300 N of force to insert a dry steel piston into a steel cylinder, the magnitude of the normal force between the piston and cylinder also equals 300 N. This force is required to overcome the static friction between the dry surfaces of the piston and the cylinder.

(b) If the steel piston and cylinder are oiled, the amount of force needed to insert the piston would decrease because the coefficient of kinetic friction is reduced. Although the exact force cannot be determined without the coefficient of kinetic friction for the oiled surfaces, it's certain that it would be less than 300 N because of the reduced friction due to lubrication.