Calculations involving forces
The The single force that could replace all the forces acting on an object, found by adding these together. If all the forces are balanced, the resultant force is zero. 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 in the same direction
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.
Example
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 in opposite directions
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.
Example
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 and vector diagrams - Higher
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.