Popular conversions
1 pairsKilogram-Meter per Second ↔ Newton-Second
kg·m/s ↔ N·s
Unit guides
2 unitsDetailed guide to Momentum
Momentum measures the 'quantity of motion' of an object and is calculated as mass times velocity: p = m × v.
Kilogram-meter per second is the SI unit of momentum, and newton-second — the unit of impulse — is dimensionally identical to it.
- Physical quantity
- Momentum
- SI unit
- Kilogram-meter per second
- SI symbol
- kg·m/s
- Formula
- p = m × v
- Typical use
- Collision analysis, propulsion and impact calculations
Momentum and impulse
Linear momentum is mass multiplied by velocity. Impulse changes momentum and is commonly expressed in newton seconds, which is dimensionally equivalent to kilogram metres per second.
Direction matters in momentum problems. This unit converter changes units only; it does not add vectors or determine a collision outcome.
What is momentum?
Momentum is a vector quantity that combines an object's mass and velocity, describing how much 'motion' it carries.
A heavy, fast-moving object has more momentum than a light, slow one — this underlies collision and impact analysis.
Conservation of momentum
In a closed system with no external net force, total momentum before and after a collision is equal — the foundation of collision analysis.
This principle also explains rocket propulsion: expelling mass at high speed in one direction gives the rocket momentum in the other.
Momentum and impulse
Impulse is the effect of a force applied over time and is measured in newton-seconds; the impulse-momentum theorem states that impulse equals the change in momentum.
Because a newton equals 1 kg·m/s², one newton-second is dimensionally identical to one kilogram-meter per second, so the two units convert one-to-one.
Unit comparison table
| Unit | Symbol | SI equivalent | System | Common use |
|---|---|---|---|---|
| Kilogram-Meter per Second | kg·m/s | SI reference unit | SI | Mechanics and collision analysis |
| Newton-Second | N·s | 1 N·s = 1 kg·m/s | Equivalent SI expression | Impulse and force-time analysis |
Momentum units
| Unit | Symbol | Information |
|---|---|---|
| Kilogram-Meter per Second | kg·m/s | View unit guide |
| Newton-Second | N·s | View unit guide |