Calculator Inputs
Example Data Table
| Drop Height | Stopping Distance | Mass | Average G | Average Force |
|---|---|---|---|---|
| 0.5 m | 5 cm | 5 kg | 10 g | 490.33 N |
| 1 m | 5 cm | 5 kg | 20 g | 980.67 N |
| 1 m | 1 cm | 5 kg | 100 g | 4903.33 N |
| 2 m | 10 cm | 5 kg | 20 g | 980.67 N |
Formula Used
Impact velocity: v = √(2gh)
Free fall time: t = √(2h / g)
Impact energy: E = mgh
Average deceleration by stopping distance: a = v² / (2s)
Average deceleration by stopping time: a = v / t
Average impact G: G = a / g
Apparent G including gravity: G = (a + g) / g
Average impact force: F = ma
In these formulas, h is drop height, g is gravity, m is mass, s is effective stopping distance, v is impact speed, and a is average deceleration.
How To Use This Calculator
- Enter the drop height and choose its unit.
- Enter object mass and choose the mass unit.
- Select stopping distance or stopping time.
- Enter the stopping distance or measured stopping time.
- Choose a gravity preset or enter custom gravity.
- Adjust efficiency, safety factor, and peak factor if needed.
- Press the calculate button to view results.
- Use CSV or PDF buttons to save the result.
What This Calculator Measures
A drop can create a large impact load even when the height looks small. This calculator estimates the average g force created when an object falls and then stops over a short distance or time. It is useful for physics lessons, product tests, packaging checks, helmet studies, and safety reviews. The result is an average value, not a peak shock reading.
Why Drop Height Matters
Drop height controls impact speed. When height rises, impact speed rises with the square root of height. Energy also rises in direct proportion to height and mass. A heavy item dropped from the same height carries more energy, so it needs more work from the stopping surface.
Stopping Distance Is Critical
The stopping distance is often the most important input. Foam, soil, suspension, crumple zones, and padding increase stopping distance. A longer stopping distance spreads the impact over more travel. This lowers average deceleration and lowers g force. A hard floor can stop motion in millimeters, so the g value can become very high.
Mass And Force
Mass does not change the g force for the same height and stopping distance. It does change force. A heavier object at the same g level creates a larger average impact force. This is why the tool includes mass and safety factor fields.
Advanced Inputs
The calculator supports common units for height, stopping distance, stopping time, and mass. You can choose a gravity preset or enter a custom gravity value. The stopping method lets you solve by crush distance or by measured stop time. Efficiency adjusts the useful stopping distance when a surface does not absorb energy evenly.
Best Use Cases
Use this calculator for estimates and comparisons. Try several stopping distances to see how padding changes the result. Compare Earth, Moon, or Mars gravity for classroom work. Use the CSV and PDF buttons when you need to save results for notes or reports.
Limits Of The Result
Real impacts are complex. Peak g can be much higher than average g. Shape, bounce, rotation, material failure, and sensor placement can change the recorded value. Use instruments for critical designs. Treat this calculator as an educational and planning aid, not as a final safety certification.
FAQs
What is g force from a drop?
It is the impact deceleration compared with gravity. A value of 20 g means the average deceleration is twenty times the selected gravity value.
Can drop height alone give g force?
No. Drop height gives impact speed and energy. You also need stopping distance or stopping time to estimate the impact g force.
Why does stopping distance affect the result so much?
A longer stopping distance spreads the impact over more movement. This lowers deceleration, g force, and impact force.
Does mass change the g force?
Mass does not change average g for the same height and stopping distance. It changes force because force equals mass times acceleration.
What is apparent G?
Apparent G includes the normal gravity load along with impact deceleration. It can be useful when estimating support or seat loading.
What is peak shock factor?
It is a multiplier used to estimate peak shock from average shock. Real impacts often have short peak loads above the average value.
Can I use this for product safety approval?
Use it for planning and education only. Safety approval needs testing, proper sensors, standards, and qualified engineering review.
Why is efficiency included?
Some materials do not absorb energy evenly. Efficiency reduces the useful stopping distance and gives a more conservative estimate.