Physics
Average force from a known impulse
Stretching the contact time reduces the average force, which is the whole principle behind airbags and crumple zones.
The Formula
F = J / t
Stretching the contact time reduces the average force, which is the whole principle behind airbags and crumple zones.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| F | Average force | newtons | Mean force over the contact period. |
| J | Impulse | newton seconds | Total momentum change required. |
| t | Time | seconds | Duration of contact. |
What Each Symbol Means
Fnewtons
Average force
Mean force over the contact period.
Jnewton seconds
Impulse
Total momentum change required.
tseconds
Time
Duration of contact.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate impulse page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Impulse, filed under Science. Every number the guide produces comes from substituting into this one line.