Momentum calculator
This momentum calculator uses p = m · v: a 2 kg body at 3 m/s has a momentum of 6 kg·m/s and a kinetic energy of 9 J. It also finds velocity from momentum and works out straight collisions between two bodies.
Example: Task: Momentum from mass and velocity · Mass m 2 kg · Velocity v 3 m/s → Result: Momentum p = 6 kg·m/s. Source: Wikipedia – Impuls. Updated: .
How it is calculated
Momentum p is the product of mass and velocity: p = m · v. It is a directed quantity measured in kg·m/s and describes how much “motion” a body carries. In an isolated system the total momentum is conserved, which is the basis for calculating collisions.
The formulas
- Momentum: p = m · v, velocity: v = p ÷ m
- Kinetic energy: E = ½ · m · v²
- Elastic collision: v1′ = ((m1 − m2) · v1 + 2 · m2 · v2) ÷ (m1 + m2), v2′ = ((m2 − m1) · v2 + 2 · m1 · v1) ÷ (m1 + m2)
- Inelastic collision: v′ = (m1 · v1 + m2 · v2) ÷ (m1 + m2) for both bodies
- Impulse: F · Δt = Δp
How to use it
Choose the task and enter the values in SI units. Example: m = 2 kg and v = 3 m/s give p = 6 kg·m/s and E = 9 J. In an elastic collision of this mass with a resting 1 kg mass the bodies move on at 1 m/s and 4 m/s; the total momentum stays 6 kg·m/s. Enter velocities against your chosen direction as negative numbers.
Frequently asked questions
How do you calculate momentum?
p = m · v, mass times velocity. A 2 kg body at 3 m/s has a momentum of 6 kg·m/s.
What is the unit of momentum?
Kilogram metre per second (kg·m/s). The newton second (N·s) is equivalent because 1 N = 1 kg·m/s².
What does conservation of momentum say?
In an isolated system without external forces the sum of all momenta stays constant. In every collision, total momentum before equals total momentum after.
What is the difference between elastic and inelastic collisions?
In an elastic collision kinetic energy is conserved too; in a perfectly inelastic one the bodies move off together and energy turns into heat and deformation.
How are momentum and force related?
Force is the rate of change of momentum: F = Δp ÷ Δt. An impulse F · Δt changes the momentum by exactly that amount.
Sources and legal basis
- Wikipedia – Impuls
- Wikipedia – Stoß (Physik)
- Wikipedia – Momentum
- Wikipedia – Elastic collision
- BIPM – SI-Broschüre (Einheiten kg, m, s, N)
As of: · Editorial policy
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