Case 1
- Force F (N)
- 50N
- Time interval Δt (s)
- 4s
200.000N·s
Open with these valuesImpulse Calculator
200.000N·s
Result: 200.000 N·sMultiply the force in newtons by the time in seconds: 50 N acting for 4 s delivers 200 N·s. That impulse equals the change in momentum, so 1 N·s is exactly 1 kg·m/s. Half the force over twice the time gives the same result.
The numbers at a glance
Held fixed: Force F (N) 50.000 N.
| Time interval Δt (s) (s) | Result (N·s) |
|---|---|
| 1.000 | 50.000 |
| 2.000 | 100.000 |
| 3.000 | 150.000 |
| 4.000Your value | 200.000 |
| 5.000 | 250.000 |
| 6.000 | 300.000 |
| 7.000 | 350.000 |
| 8.000 | 400.000 |
Worked examples
Case 2
- Force F (N)
- 100N
- Time interval Δt (s)
- 0.5s
50.000N·s
Open with these valuesCase 3
- Force F (N)
- 25N
- Time interval Δt (s)
- 8s
200.000N·s
Open with these valuesHow it's calculated
J = F × Δt
- StepEnter the constant force in newtons; a negative value points the other way.
- StepEnter how long the force acts, in seconds.
- ResultRead the impulse in newton-seconds, identical to kg·m/s of momentum.
Reference table
| F (N), Δt (s) | What it describes | Impulse (N·s) |
|---|---|---|
| 3.5, 2 | A gentle push held for two seconds | 7 |
| 10, 2 | A small shove | 20 |
| 100, 0.5 | A sharp hit lasting half a second | 50 |
| 50, 4 | A steady 50 N for four seconds | 200 |
| 25, 8 | Half the force, twice as long — same result | 200 |
| -50, 4 | The same push acting the other way | -200 |
Questions
What is impulse?
Impulse is the effect of a force applied over a time interval: J = F × Δt, newtons times seconds, giving newton-seconds. It measures how much a push or pull changes an object's motion. A 50 N force acting for 4 s delivers 200 N·s.
How is impulse related to momentum?
Impulse equals the change in momentum, J = Δp, which is why the units match: 1 N·s is exactly 1 kg·m/s. A 200 N·s impulse changes the momentum by 200 kg·m/s, whether it came from a big force over a short time or a small force over a long one. That impulse-momentum theorem is the practical heart of the formula.
What are the units of impulse?
Newton-seconds (N·s), which is identical to kilogram-metres per second (kg·m/s), the unit of momentum. Both describe the same quantity from two angles: N·s stresses force × time, kg·m/s stresses mass × velocity. Keep force in newtons and time in seconds and the answer is in N·s directly.
Why do airbags and crumple zones reduce force?
In a crash the change in momentum is fixed, so the impulse F × Δt is fixed too. Stretching the collision over more time means the force must drop to keep the product the same. Airbags, crumple zones and bending your knees on landing all lengthen the contact time and lower the peak force.
Can the force or the impulse be negative?
Yes, both are directional, so a negative value simply means the force acts the other way along your chosen axis — a braking force, for example. A negative impulse reduces momentum in that direction. The time interval, however, must be positive.
Sources and last check
Information, not professional advice.