BIZOMAT MAKEOS · Mechanics
Impact Energy and Stopping Force
What energy and force result when this mass is stopped over a short distance?
Impact energy of a falling or moving mass and the average and linear-spring peak forces when it is stopped over a given distance.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Situation | choice | Falling mass or a mass moving horizontally into a stop. |
| Mass | kg | Mass of the moving or falling body. |
| Drop height before contact | mm | Height of the fall before contact (falling only). |
| Speed at contact | m/s | Speed at the moment of contact (moving only). |
| Stopping distance | mm | Distance over which the body is brought to rest: buffer stroke, deflection or crush depth. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Situation
- What it is
- Whether the body falls onto the stop from a height, or moves horizontally into the stop at a known speed.
- Units and format
- Choose one of 2 options from the list: Falling mass (from a height); Moving mass (horizontal, at a speed).
- Example
- The form opens with “Falling mass (from a height)” selected as a worked example. Choose the option that matches your case.
- Get it right
- Only the input for the chosen situation is used: drop height for falling, speed for moving.
What this means: Mass
- What it is
- The mass of the body that hits the stop and must be brought to rest.
- Units and format
- Enter a number in kg: kilograms. The form accepts 0.000001 kg to 10000000 kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 50 kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The energy and stopping force rise in proportion to the mass.
- Get it right
- Include everything that moves with the body, such as a carriage, fixture or load.
What this means: Drop height before contact
- What it is
- How far the body falls freely before it first touches the stop. Used only for a falling mass.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 1000000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 300 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Measure to first contact; the tool adds the fall through the stopping distance itself.
What this means: Speed at contact
- What it is
- The speed of the body at the moment it first touches the stop. Used only for a moving mass.
- Units and format
- Enter a number in m/s: metres per second. The form accepts 0 m/s to 1000 m/s. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1.5 m/s as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The energy rises with the square of the speed.
- Get it right
- Use the real speed at contact, which may be higher than the nominal conveyor or axis speed.
What this means: Stopping distance
- What it is
- The distance over which the body is brought to rest after contact: the buffer or shock absorber stroke, spring deflection or crush depth.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 100000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The average and peak stopping forces fall as the stopping distance increases.
- Get it right
- A small error here matters: halving the stopping distance roughly doubles the stopping force.
Method and formulas
- Falling: v = √(2gh); energy E = m g (h + s), including the fall through the stopping distance.
- Moving: E = ½ m v².
- Average force = E ÷ s; a linear spring stop peaks at 2E ÷ s.
- Example: 50 kg falling 300 mm onto a 10 mm stop must absorb 152 J, averaging 15,200 N.
Limitations
- Rigid bodies and a known stopping distance are assumed; real stops have non-linear characteristics.
- Rebound and energy lost elsewhere are ignored, which is conservative for the stop.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size end stops, buffers and shock absorbers
- Estimate the load from a dropped part or tool
- Compare stopping distances
Who it is for
- Design engineers
- Maintenance engineers
- Technicians
What you get
- Impact speed
- Energy to absorb
- Average stopping force
- Peak force for a linear spring stop
- Deceleration
Interpreting the result
- Select a buffer or absorber rated for the energy per stroke and the peak force, at your cycle rate.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 179–186, 278. Topic reference; no source tables or recommended settings are reproduced.
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