Momentum Calculator
Momentum50.000 kg·m/s
Linear momentum measures the "quantity of motion" an object carries: the product of its mass and its velocity. This calculator multiplies a mass in kilograms by a velocity in metres per second to return momentum in kilogram-metres per second (kg·m/s). It is useful for analysing collisions, recoil, and any situation governed by conservation of momentum.
Formula
p = m × v
- p
- Linear momentum in kilogram-metres per second (kg·m/s)
- m
- Mass of the object in kilograms (kg)
- v
- Velocity in metres per second (m/s); sign indicates direction
How it works
- Enter the object's mass in kilograms (kg).
- Enter its velocity in metres per second (m/s); use a negative value if it moves in the opposite direction.
- The calculator computes p = m × v and returns the momentum in kg·m/s, rounded to three decimal places.
Worked example
A 1,200 kg car travels at 15 m/s. Find its momentum.
- Identify mass m = 1200 kg and velocity v = 15 m/s.
- Multiply: 1200 × 15 = 18,000.
p = 18,000 kg·m/s in the direction of travel.
Frequently asked questions
- What is the difference between momentum and kinetic energy?
- Momentum (p = mv) is a vector that scales directly with velocity and is conserved in collisions. Kinetic energy (½mv²) is a scalar that scales with velocity squared and is only conserved in perfectly elastic collisions.
- Why does direction matter for momentum?
- Momentum is a vector quantity, so velocity carries a sign. Enter a negative velocity for motion in the opposite direction; this matters when you add the momenta of two objects approaching each other.
- What units does this calculator use?
- Mass is entered in kilograms and velocity in metres per second, so momentum is reported in kilogram-metres per second (kg·m/s), the SI unit of momentum.
- How does momentum relate to impulse?
- Impulse equals the change in momentum: J = Δp = FΔt. A force applied over time changes an object's momentum, which is why airbags and crumple zones extend the impact time to reduce force.