When adding vector quantities, however, the direction must be taken into account.
Adding Forces
Forces are represented by lines drawn to scale. Its direction it the direction of the vector quantity. If we have a force of 5 N east we may use a scale where 1cm represents 1N. Therefore, the 5N force would be represented by a 5cm line.
Below we have three examples. In each case we have to add forces of 3N and 4N. We will calculate the resultant force of each.
Example1:
In this example, the two forces are parallel and in the same direction. Therefore, they produce a resultant force of: 4N + 3N = 7N, to the right. Note, you must state the direction.
Example 2:
In this example, the two forces are in exactly opposite directions. The resultant force is therefore: 4N - 3N = 1N, to the right. Note, you must state the direction.
Example 3:
Example 4:
In these cases, the Principle of Parallelogram of Forces must be applied. This principle states that if the two forces are represented in size and direction by the sides of a parallelogram drawn to scale, the resultant force is represented by the the diagonal drawn from the point where the force acts.
In these cases, the Principle of Parallelogram of Forces must be applied. This principle states that if the two forces are represented in size and direction by the sides of a parallelogram drawn to scale, the resultant force is represented by the the diagonal drawn from the point where the force acts.
This video should show you how to calculate the resultant vector. If you still do not get it, you can use YouTube.
