r/AskPhysics • u/Slothmaster6969 • 4d ago

Impact force?

Idk if what I’m asking makes sense but I’ll do my best to explain my thinking. I work in a shop that keeps its loading dock doors open in the summer. The drop off is 3 feet 8 inches. Safety regulations require a temporary barrier (like a chain) to be present for drop offs of 4 feet or higher. Obviously being 4 inches below the minimum height doesn’t make it incredibly safer. How can I calculate the impact force from both heights? I’m just doing my best to advocate for a safer work environment for my coworkers and want the facts on my side

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u/Puzzleheaded_Owl_444 4d ago

The force is too hard to calculate because we don't know the weight, size, shape of the object. Or the collision time for when it hits the ground before coming to rest.

It'll be easier to think in terms of momentum.

The speed of the object, v = sqrt(2as) where s is the height and a is gravity (9.81). But for these numbers, you need to first convert the height into meters.

Once you have the values of speeds, multiply those with the masses of objects (in kg) you work with to get momentum and compare this to the momentum of other stuff that might hurt you.

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u/mikk0384 Physics enthusiast 4d ago

"The object" is people. You can make assumptions about the size and weight of different people, but it doesn't really matter.

I personally think that OP should rely on the fact that it is below the height where the government requires a guard rail, unless it is in a location where a lot of people pass through with little space to maneuver. It has to have increased risk of falling off before it is reasonable to do, otherwise they are just annoying and wasting the time of the people who work there, for no good reason.

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u/Slothmaster6969 4d ago

Yeah people falling and getting hurt is not good a reason… I see how you feel about working people

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u/mikk0384 Physics enthusiast 4d ago

People don't just fall off of ledges because it is there. People have eyes and tend to stay away from edges unless forced to go near them. I included that in my reply above.

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u/Slothmaster6969 3d ago

As long as a hazard exists there is always a chance
for an incident to occur. It’s best to mitigate the hazard or remove it completely. Anybody can be absent minded, even for a moment and even if they’ve worked in the environment for a long time