How this calculator works
Impulse is the time integral of net force. Using average force gives the same total impulse even if contact force varies during impact. The momentum-change form requires constant mass. Enter signed velocities along one axis so reversing direction is counted correctly. A newton second is equivalent to a kilogram metre per second; neither is a unit of energy.
Formula
J = delta p = m(vf-vi) = F_average delta t.
Worked example
Changing a 2 kg object from -1 to 4 m/s requires 10 N s of impulse. An impulse of 12 N s delivered in 3 s corresponds to an average force of 4 N.
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Frequently asked questions
Does this calculate peak force?
No. The force result is an average over the entered time interval.
Which force should I enter?
Use the net external force along your chosen axis, including all contributions during the interval.
Can impulse be negative?
Yes. It means the momentum change points opposite your positive axis.