**The net force of an object can be determined if the mass and acceleration are known.** Net force is determined by multiplying the mass of the object by its rate of acceleration.

Net force is the vector sum of all the individual forces and determination of force involves the application of Newton's Second Law of Motion which is represented by the equation: F_{net}=m*a or simply F=ma. In this equation,

- li]F is the force measured in Newtons
- m is the mass measured in kilograms (kg)
- a is the acceleration measured in meters per second (m/s
^{2}

Rearranging the equation, 1 Newton is equal to 1 kg-m/s^{2} or the amount of force required to accelerate 1 kg of the object for one meter per second squared.

The net external force of a falling object may be complicated by several issues including the drag force of the atmosphere. However, an object falling in a vacuum, or free falling, is subject to only one external force, gravity, which is expressed as weight. The weight of an object is represented by the equation W=m*g or W=mg. In this equation,

[u]li]W is weightThe net external force of a free falling object is equal to its weight.

- li]if F=ma and F=W
- then a=W/m
- a=W/m=(m*g)/m=g[/i]

Acceleration is therefore equal to gravitational force.