Identify the surface the object is in contact with
Draw a free-body diagram
Find all forces perpendicular to the surface
Use Newton’s second law in the perpendicular direction
If there is no acceleration perpendicular to the surface, set the net perpendicular force equal to zero
On a horizontal surface with no other vertical forces, normal force equals weight: N = mg
If an extra downward force acts, add it to the weight
If an extra upward force acts, subtract it from the weight
On an incline, use the perpendicular component of weight: N = mg cos θ
If there are other forces at an angle, include their perpendicular components
Solve the equation for N