# How to calculate the impact energy of a door hitting a door

• David Walker
In summary, the conversation discusses a scenario where a glass door is being caught by the wind and slamming against a door stop, causing it to shatter. The goal is to determine the impact energy and equivalent static force of the door hitting the stop. However, the necessary equations and information are not readily available and it is believed that the calculation would be too complex to solve.
David Walker
Could someone help me with this problem?

I have a scenario where a glass door is being caught by the wind and slamming against a door stop and shattering. I would like to work out the impact energy of the door hitting the stop, and if possible an equivalent static force.

The door is 1.5m wide, 3.0m high and constructed of 15mm glass, (170kg total weight).
The wind load is 2.14kN/m^2
The door opens 90 degrees with the door stop 350mm from the pivot. The pivot is 100mm in from the edge of the door.

Thank you.

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Can you find any relevant equations? Can you draw a free body diagram?
Do you think your employer would approve you seeking solutions to problems on their pad?

I don't believe it's possible to calculate a solution with just the info given.

The force will depend to a great extent on the properties of the door stop and the door. If you assume the door stops moving the instant it hits the stop then the calculated force is theoretically infinite. Obviously the door doesn't stop instantly. I suspect what happens is that the bottom of the door stops quickly but the centre of mass of the door continues and this twists the door. In effect you have a glass torsional "spring" that decelerates the door.

There is probably a way to calculate how the door moves when it hits the stop but it will be quite complicated - too hard for me!

## 1. How do I calculate the impact energy of a door hitting a door?

To calculate the impact energy of a door hitting a door, you will need to know the mass and velocity of the door. The formula for calculating impact energy is 1/2 * mass * velocity^2. You can use a scale to determine the mass of the door and a stopwatch to measure its velocity. Once you have these values, plug them into the formula to calculate the impact energy.

## 2. What units should I use for mass and velocity when calculating impact energy?

When calculating impact energy, you should use the metric system and use kilograms for mass and meters per second for velocity. This will ensure that your calculations are accurate and consistent.

## 3. Can I use the same formula to calculate the impact energy of any object?

Yes, the formula for calculating impact energy (1/2 * mass * velocity^2) can be used for any object. Just make sure to use the correct units for mass and velocity and to measure them accurately.

## 4. Is there a maximum impact energy that can be generated by a door hitting a door?

Yes, there is a maximum impact energy that can be generated by a door hitting a door. This value depends on the mass and velocity of the door. The heavier and faster the door, the higher the impact energy will be.

## 5. How can I reduce the impact energy of a door hitting a door?

To reduce the impact energy of a door hitting a door, you can decrease the mass and/or velocity of the door. This can be achieved by using a lighter door or closing it more slowly. You can also add padding or cushioning to the doors to absorb some of the impact energy.

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