Impulse Calculator
Calculate impulse from force and time, or from a change in momentum, using the impulse–momentum theorem.
How it works
- 1Choose your method — “Force and time” uses J = F·Δt, while “Momentum change” uses J = m·(v − u).
- 2Enter your values in metric or imperial units; the calculator converts everything to SI.
- 3The result is shown in N·s (newton-seconds), identical to kg·m/s — the SI unit of momentum.
Use cases
- Crash-test engineering — the impulse a seatbelt or airbag must absorb to protect an occupant.
- Sports science — the impulse a bat or racquet delivers to a ball during a short contact.
- Rocket propulsion — the total impulse a thruster delivers over a burn.
Frequently asked questions
What is impulse, and what is its formula?
Impulse (J) is the net force times the time it acts: J = F·Δt, in newton-seconds (N·s). A constant 50 N force for 0.2 s gives 50 × 0.2 = 10 N·s.
What is the impulse–momentum theorem?
It states that the impulse equals the change in momentum: J = F·Δt = Δp = m·(v − u). Impulse and momentum change are numerically equal and share the unit N·s = kg·m/s.
When should I use the momentum-change method?
Use it when you know the mass and the initial and final velocities but not the force. A 0.5 kg ball going from rest to 20 m/s receives 0.5 × (20 − 0) = 10 N·s, regardless of contact time.
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