How Do You Calculate Net Force?

Paul L Dineen/CC-BY-2.0

To calculate the net force, or unbalanced force, of a Newtonian object, find the sum of all forces presently acting upon it. These include gravity, friction and other forces depending on the scenario. You need only a few figures and computations to calculate an object’s net force, which is required for acceleration and is expressed in Newtons.

  1. Draw a free-body diagram of your object

    To help keep track of the forces involved, create a free-body diagram, which is a simple sketch of the object and the forces acting upon it. Draw a rough diagram of the object, and then use arrows to indicate the direction of each force.

  2. Identify the forces

    Identify the forces acting on your object. Note that some forces cancel each other out and have no bearing on your total Newtonian net force. Forces are identified according to the condition, environment and behavior of an object.

  3. Add these forces together

    Find the sum of these relevant forces by applying their force, in Newtons, to your diagram. Forces moving toward the right in the free-body diagram are considered positive forces, and those moving toward the left are negative. Add the forces together. The result is the Newtonian net force.