How to Figure the Direction of Force
- 1). Draw a free body diagram. This is a diagram that uses arrows to label the direction of various forces acting on a single body. This includes forces acting in the horizontal and vertical directions.
- 2). Find the sum of the forces in the horizontal and vertical directions. As an example, assume the vertical forces acting on a body are 980 Newtons (N), 370 N and -500 N (the negative denotes it is in the opposite direction), and the horizontal forces are 350 N and -100 N. Adding the vertical and horizontal forces together results in a total vertical force of 850 N and 250 N.
- 3). Divide the vertical component of the force by the horizontal component of the force. In the example above, dividing 850 N by 250 N gives 3.4. Call this result A.
- 4). Calculate the inverse tangent of result A. This can be found by inputting the number into a scientific calculator, pressing the "2nd" button, then the "tan" button (the inverse tangent may vary for different types of calculators). Calculating the inverse tangent of 3.4 gives 73.6 degrees. This is the direction that the resultant force is applied in.
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