The resultant force is a single force that has the same effect as two or more forces acting together. You can easily calculate the resultant force of two forces that act in a straight line.
Two forces that act in the same direction produce a resultant force that is greater than either individual force. Simply add the magnitudes of the two forces together.
Two forces, 3 newtons (N) and 2 N, act to the right. Calculate the resultant force.
3 N + 2 N = 5 N to the right
Two forces that act in opposite directions produce a resultant force that is smaller than either individual force. It is often easiest to subtract the magnitude of the smaller force from the magnitude of the larger force.
A force of 5 N acts to the right, and a force of 3 N act to the left. Calculate the resultant force.
5 N - 3 N = 2 N to the right
Free body diagrams are used to describe situations where several forces act on an object. Vector diagrams are used to resolve (break down) a single force into two forces acting at right angles to each other.