Newton's Laws of Motion

1st Law

An object will remain at rest or move at constant velocity (linear equilibrium), unless acted upon by an resultant external force.

If object is not moving, there is no resultant force

2nd Law

The resultant external force acting on an object is equal to the rate of change of momentum of the object.

F=m(v−u)t=ma\begin{align*} F &= \frac{m(v-u)}{t} \\ &= ma \end{align*}

3rd Law

If object A exerts a force on object B, object B exerts a force on object A of equal magnitude in the opposite direction.

Come in pairs
Have the same type (electromagnetic, gravitational, weak nuclear, strong nuclear)
Act on different bodies