Calculate momentum

Add two signed linear momenta and calculate the shared velocity after a perfectly inelastic collision.

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ToolMomentum Calculator
Input
Output
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How it works

Each momentum is mass × velocity, total momentum is their signed sum, and shared velocity divides total momentum by combined mass. The result assumes the objects stick together and external impulse is negligible.

  • One-dimensional signed velocity encodes direction.
  • No elastic-collision energy equation is included.

Worked example

A trolley hits a stationary one
5kg at 4 m/s hits a stationary 3kg trolley and they couple together
Input
											Mass1 kg: 5
Velocity1 metres per second: 4
Mass2 kg: 3
Velocity2 metres per second: 0
Output
												Momentum1 kg ms: 20
Momentum2 kg ms: 0
Total momentum kg ms: 20
Final velocity metres per second: 2.5
Impulse on mass1 newton seconds: -7.5

When to use this

Cart-collision exercises check conservation, recoil estimates add signed momenta, and lessons find shared speed after objects stick.

Edge cases

  • Opposite velocities cancel when signed, so equal opposing momenta can produce zero shared speed.
  • A zero combined mass is rejected because final velocity is undefined.
  • An elastic collision generally leaves different final velocities and needs a different model.