🎳 Momentum Calculator (p = mv)
Find momentum from mass and velocity (p = mv), or solve for mass or velocity.
Momentum p
30 kg·m/s
Momentum p = m·v. Impulse J = F·Δt equals the change in momentum (J = Δp). 🔒 Computed in your browser.
How the momentum calculator (p = mv) works
Linear momentum is p = mv, the product of mass and velocity. Enter any two of momentum, mass and velocity and the tool solves for the third. Impulse (force × time) equals the change in momentum.
Momentum is conserved in collisions, which is why it matters. Impulse J = FΔt = Δp connects a force acting over time to the momentum change.
Frequently asked questions
What is momentum?
Momentum p = mv is mass times velocity, a measure of how hard it is to stop a moving object. It is a vector (has direction) and its SI unit is kg·m/s.
How do I calculate momentum?
Multiply mass by velocity: a 2 kg object at 15 m/s has p = 30 kg·m/s. Enter mass and velocity to compute it.
What is impulse?
Impulse is force times the time it acts, J = FΔt, and it equals the change in momentum (J = Δp = m(v − u)). A small force over a long time can produce the same impulse as a large force briefly.
Is momentum conserved?
In an isolated system (no external net force), total momentum is conserved, the basis for analysing collisions and explosions.
What is the difference between momentum and kinetic energy?
Both depend on mass and velocity, but momentum (mv) is a vector conserved in all collisions, while kinetic energy (½mv²) is a scalar conserved only in elastic collisions.
Worked example: a recoiling rifle
By conservation of momentum, a 4 kg rifle firing a 0.02 kg bullet at 400 m/s recoils at v = (0.02 × 400)/4 = 2 m/s in the opposite direction, since the total momentum stays zero.
What are the units of momentum?
Kilogram-metres per second (kg·m/s), with mass in kg and velocity in m/s. Momentum has no named unit of its own; impulse shares the same unit because it equals a change in momentum.
Why do airbags and crumple zones reduce injury?
They extend the time over which momentum changes. Since the impulse J = FΔt = Δp is fixed by the crash, a longer stopping time means a smaller peak force on the occupants, the whole point of the impulse, momentum relationship.
Is momentum a vector?
Yes, momentum has both size and direction, pointing the same way as the velocity. In two dimensions you add the components separately, and in a collision the total momentum in each direction is conserved.