Momentum Calculator
Calculate linear momentum using p = m × v with related kinetic energy.
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Quick Tip
Enter the mass in kilograms.
About This Tool
Why use Momentum Calculator?
Momentum is mass times velocity: p = m × v, measured in kilogram-metres per second. Enter the mass and velocity and the calculator returns the momentum, the matching kinetic energy (p² ÷ 2m) and the de Broglie wavelength.
A 1,500 kg car at 20 m/s has 30,000 kg·m/s of momentum. In a closed system momentum is conserved, which is the principle behind collision problems: the total before a crash equals the total after. The de Broglie wavelength, h ÷ p with Planck's constant h = 6.626 × 10⁻³⁴, is vanishingly small for everyday objects and only becomes significant for particles.
Key Benefits
Momentum and kinetic energy together
Both are derived from the same inputs, so collision questions that ask for both are covered in one step.
Direction respected
Momentum is a vector, so negative velocities produce negative momentum — essential for head-on collision sums.
De Broglie wavelength included
The quantum relationship λ = h ÷ p is calculated for particle physics problems.
How to use Momentum Calculator
- 1
Enter the mass in kilograms.
- 2
Enter the velocity in m/s, using a negative value for the opposite direction.
- 3
Read the momentum in kg·m/s.
- 4
Use the kinetic energy shown alongside when a question asks for both quantities.
Best use cases
Solve conservation of momentum problems for collisions.
Compare the momentum of two vehicles of different mass.
Work out impulse, which is the change in momentum.
Calculate a de Broglie wavelength in modern physics coursework.
Momentum Calculator FAQs
What is the momentum formula?
p = m × v. A 2 kg object at 5 m/s has 10 kg·m/s of momentum.
What does conservation of momentum mean?
With no outside forces, the total momentum before an interaction equals the total after. Two objects that collide and stick together share the combined momentum they started with.
How are momentum and kinetic energy different?
Momentum is mv and has direction; kinetic energy is ½mv², is always positive and depends on the square of velocity. Momentum is conserved in every collision, but kinetic energy is only conserved in elastic ones.
What is impulse?
The change in momentum, equal to force multiplied by the time it acts. Spreading a collision over more time — crumple zones, airbags — lowers the force for the same impulse.
Related Physics Tools
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