Calculator Inputs
Formula Used
| Metric | Formula | Meaning |
|---|---|---|
| Impact velocity | v = √(v₀² + 2gh) |
Finds velocity just before impact from initial downward speed, gravity, and drop height. |
| Fall time | t = (v - v₀) / g |
Estimates how long the fall lasts when gravity is constant. |
| Kinetic energy | KE = 0.5 × m × v² |
Measures impact energy immediately before stopping begins. |
| Average force by distance | F = KE / d = m × v² / (2d) |
Uses stopping distance to estimate average impact force. |
| Average force by time | F = m × v / Δt |
Uses stopping time to estimate average impact force. |
| Average deceleration | a = v² / (2d) or a = v / Δt |
Shows average slowdown during impact. |
| g-load | g-load = a / g |
Expresses deceleration as multiples of gravity. |
These formulas estimate average impact values. Real collisions often create non-uniform force spikes, material deformation, vibration, and heat loss.
How to Use This Calculator
- Enter the falling object's mass and choose the mass unit.
- Enter the drop height and optional initial downward speed.
- Set gravity. Use 9.81 m/s² for Earth unless another environment is required.
- Provide stopping distance, stopping time, or both for impact analysis.
- Optional: add a safety factor to estimate a more conservative design force.
- Click Calculate Impact Force to show results above the form.
- Review speed, energy, momentum, force, g-load, and the graph.
- Use the export buttons to download the current results as CSV or PDF.
Example Data Table
| Mass | Height | Stopping Distance | Impact Velocity | Average Force |
|---|---|---|---|---|
| 1 kg | 1.0 m | 0.02 m | 4.43 m/s | 490.50 N |
| 5 kg | 2.0 m | 0.03 m | 6.26 m/s | 3,270.00 N |
| 20 kg | 1.5 m | 0.05 m | 5.42 m/s | 5,886.00 N |
| 80 kg | 3.0 m | 0.08 m | 7.67 m/s | 29,430.00 N |
Frequently Asked Questions
1. What does this calculator estimate?
It estimates fall time, impact velocity, kinetic energy, momentum, average impact force, deceleration, and g-load. It uses your chosen mass, height, gravity, and stopping inputs.
2. Why does stopping distance matter so much?
A shorter stopping distance means the object must lose its motion more abruptly. That raises average deceleration and average force sharply, even if the fall height stays the same.
3. Is the displayed impact force exact?
No. It is an average estimate. Real impacts can produce higher peak forces because materials compress unevenly, rebound, crack, bend, or spread the collision over changing contact conditions.
4. Can I use stopping time instead of stopping distance?
Yes. If you know how long the object takes to stop, the calculator uses impulse-momentum to estimate average force. If you know both, compare both methods for reasonableness.
5. Does mass always increase impact force?
Yes, when other conditions stay the same. More mass means more momentum and more kinetic energy, which increases the force required to stop the object over the same time or distance.
6. What happens if I enter an initial downward velocity?
The calculator adds that starting speed to the speed gained during the fall. That raises impact velocity, energy, momentum, and usually the estimated impact force.
7. Does this include air resistance?
No. The model assumes ideal motion under constant gravity. For long falls, light objects, or high-speed cases, air resistance can reduce real impact velocity significantly.
8. When should I apply a safety factor?
Use a safety factor for design, protection, packaging, mounts, supports, or structural checks. It gives a more conservative force target when uncertainty or variable impact conditions exist.