How this calculator works
A measured velocity change gives average acceleration. Multiplying by constant mass gives average net force, including gravity, friction and any applied forces in their signed sum. In the inverse velocity modes the force is assumed constant throughout the interval. Variable-mass systems such as rockets need momentum accounting beyond this simple form.
Formula
Faverage = m(v-u)/t; aaverage = (v-u)/t; v = u+Ft/m.
Worked example
A 10 kg object changing from 2 to 8 m/s in 3 s has average acceleration 2 m/s² and average net force 20 N. A 5 kg object under 10 N for 4 s gains 8 m/s.
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Frequently asked questions
How is this different from the force calculator?
This page starts with initial and final velocities and elapsed time, so it also derives acceleration.
Does negative force mean braking?
Only if velocity points in the positive direction. Force and velocity signs together determine whether speed increases or decreases.
Does the force need to be constant?
The forward result is average force. Inverse predictions of velocity assume constant force over the interval.