KEVOS® MAKEOS · Mechanics
Impulse, Momentum and Collisions
What average force changes this body’s velocity in the time available, and how do two bodies move after they collide?
Average force from the change in momentum over a time (linear impulse), and the velocities of two bodies after a direct central impact with a coefficient of restitution, with the kinetic energy lost.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Calculation | choice | Choose the calculation. |
| Mass (force mode) | kg | Mass of the body. |
| Initial velocity | m/s | Velocity at the start (signed along one line). |
| Final velocity | m/s | Velocity at the end (signed). |
| Time the force acts | s | Duration of the force (stopping or acceleration time). |
| Mass of body 1 | kg | Mass of the first body. |
| Velocity of body 1 before impact | m/s | Its velocity before impact (signed). |
| Mass of body 2 | kg | Mass of the second body. |
| Velocity of body 2 before impact | m/s | Its velocity before impact (signed). |
| Coefficient of restitution | 1 for a perfectly elastic impact, 0 for perfectly plastic (bodies move together); measure or estimate for your materials. |
Method and formulas
- Linear impulse equals the change in momentum: F t = m (v_f − v₀).
- Collision: v₁′ = [m₁v₁ + m₂v₂ − m₂ e (v₁ − v₂)] ÷ (m₁ + m₂) and v₂′ = [m₁v₁ + m₂v₂ + m₁ e (v₁ − v₂)] ÷ (m₁ + m₂).
- Energy lost = initial minus final kinetic energy.
- Example: 10 kg from 0 to 5 m/s in 0.1 s needs an average force of 500 N.
Limitations
- Average force only; peak force in an impact is usually several times higher.
- Direct central impact along one line.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Estimate the force on a stop or buffer from the stopping time
- Predict the rebound after two parts collide
- Estimate the energy absorbed in an impact
Who it is for
- Design engineers
- Mechanical engineers
- Engineering students
What you get
- Average force or velocities after impact
- Momentum
- Kinetic energy lost
Interpreting the result
- A softer buffer that lengthens the stopping time lowers the force in proportion.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 184–186. Topic reference; no source tables or recommended settings are reproduced.
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