Question

When rebuilding her car's engine, a physics major must exert 445 N of force to insert a dry steel piston into a steel cylinder. What is the magnitude of the normal force in newtons between the piston and cylinder?

b) What is the magnitude of the force in newtons she would have to exert if the steel parts were oiled?

Answer 1

Part A.

We know that friction force is given by:

Ff = *N

N = Ff/

Ff = friction force = 445 N

= Coefficient of kinetic friction between dry piston and cylinder = 0.3

So,

N = 445/0.3 = 1483.33

N = magnitude of normal force = 1483 N

Part B.

Now when steel parts were oiled, then

= Coefficient of kinetic friction between oiled piston and cylinder = 0.03

N = 1483.33 N, So

Ff = *N = 0.03*1483.33

Ff = 44.5 N = friction force exerted

Let me know if you've any query.