Advanced Impact Force Form
Example Data Table
| Vehicle Mass | Speed | Distance | Time | Energy Transfer | Use Case |
|---|---|---|---|---|---|
| 1200 kg | 30 km/h | 0.40 m | 0.10 s | 55% | Low speed estimate |
| 1500 kg | 40 km/h | 0.35 m | 0.08 s | 60% | Urban impact estimate |
| 2200 kg | 55 km/h | 0.25 m | 0.06 s | 70% | Higher energy estimate |
Formula Used
Relative speed: v = (vehicle speed - person speed) × cos(angle)
Reduced mass: m = (vehicle mass × person mass) ÷ (vehicle mass + person mass)
Kinetic energy: E = 0.5 × m × v²
Force from distance: F = transferred energy ÷ stopping distance
Force from impulse: F = momentum change ÷ impact time
Peak force: peak force = average force × peak factor × safety factor
Pressure: pressure = peak force ÷ contact area
How to Use This Calculator
- Enter the vehicle mass in kilograms.
- Enter the person effective mass in kilograms.
- Add vehicle speed and choose the correct speed unit.
- Enter person speed if the person is moving in the same direction.
- Add stopping distance or crush distance in meters.
- Enter contact time, contact area, angle, and adjustment factors.
- Press the calculate button to view results above the form.
- Use the CSV or PDF button to save the result.
Understanding Car Impact Force
What the Calculator Estimates
A car impact force estimate depends on mass, speed, stopping distance, and contact time. This calculator compares two useful physics paths. One path uses kinetic energy and stopping distance. The other path uses momentum and impact time. The final result blends both paths, then applies peak and safety factors. This gives a practical educational estimate for classroom work, safety studies, and early engineering review.
Why Speed Matters
Speed has a strong effect because kinetic energy rises with the square of velocity. Doubling speed can create about four times the energy, before other factors change. That is why small speed increases can greatly raise impact force. A lower speed often gives the body, vehicle, and surface more time to absorb energy.
Role of Stopping Distance
Stopping distance is the distance over which the motion is reduced. It may include vehicle crush, body movement, clothing compression, and surface deformation. A larger distance spreads energy over more movement. This usually lowers average force. A short distance creates a sharper force rise.
Impact Time and Impulse
Impact time controls impulse force. A longer contact time spreads momentum change. A shorter contact time creates a larger average force. Real crashes have changing force curves. The peak force can be much higher than the average force. The peak factor helps represent that difference.
Using Careful Assumptions
This calculator is not a medical or legal decision tool. Real impacts involve posture, bumper height, braking, rotation, road friction, and secondary contact. Use conservative assumptions when results matter. Compare several scenarios instead of trusting one value. Treat the output as an estimate, not a final reconstruction. Professional analysis needs measured data, validated models, and expert review.
FAQs
What does this calculator measure?
It estimates impact force using mass, speed, stopping distance, impact time, and contact area. It also reports energy, impulse, deceleration, pressure, and a simple estimate level.
Is this result exact?
No. It is an educational estimate. Real impacts depend on body position, vehicle shape, braking, road conditions, deformation, and secondary impacts.
Why is stopping distance important?
Stopping distance spreads the impact energy over movement. A larger stopping distance usually lowers average force. A smaller stopping distance usually raises force.
What is impact time?
Impact time is the contact duration during the collision. Shorter times create larger impulse forces. Longer times spread momentum change over more time.
What is peak force factor?
Peak force factor estimates how much higher peak force may be than average force. Real collisions have force curves, not one constant force value.
Why use reduced mass?
Reduced mass helps model interaction between two bodies. It gives a practical collision mass when both the vehicle and person are part of the motion exchange.
Can this be used for legal cases?
No. It should not replace crash reconstruction, legal advice, medical review, or expert testing. It is only for learning and rough scenario comparison.
Can I download the result?
Yes. After calculation, use the CSV button for spreadsheet data. Use the PDF button to save a simple report.