#### Weight

w = mg

where m = mass and g = acceleration due to gravity (–9.8m/s^{2} on Earth).

#### Newtons

1N = 1kg*m/s^{2}

1N = 0.2248lbs

#### Static Friction

F_{S} = –μ_{S}N

where N is the normal force.

#### Kinetic Friction

F_{K} = –μ_{K}N

where N is the normal force.

#### Free-Body Diagram

Use arrows of relative lengths to represent forces.

Draw all arrows originating from the center of the object and pointing in the appropriate direction.

#### Newton's First Law

If F_{net} = 0, no change in motion occurs.

#### Newton's Second Law

F_{net} = ma

where m is mass and a is acceleration.

#### Newton's Third Law

For every force there is an equal and opposite force, or, when two objects come into contact, they exert equal and opposite forces upon each other.