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I need to describe the relative magnitude of a force using real-life comparisons instead of numbers.

I work in engineering, we install some Devices on a flat surface and my task is to periodically check how stable the Devices are. Specifically, I push them with my hand to see if they will tilt, spin, rock or move. I now need to provide a report. There is no specific method for checking the Devices, or for the subsequent reporting, but I am trying to improve our practice.

The Devices are roughly the shape and size of a box of six eggs, or 500 grams of margarine, glued down onto a flat, horizontal surface. The largest face is horizontal.

The best way I can describe it for now:


Option 1

  1. The first Device only moved/tilted when I applied the force needed to tip over a washing machine.
  2. The second Device moved/tilted when I applied the force needed to tip over a 5ltr/1gal bottle of water.
  3. The third Device moved/tilted when I applied the force needed to tip over a 500g/16oz tub of butter.

The above examples sound silly and totally unsuitable for a professional report.

Option 2

  1. A normal Device only moved/tilted when I applied the force needed to tip over a washing machine.
  2. The second Device moved/tilted when I applied around a tenth of the force needed to tip over a normal one.
  3. The third Device moved/tilted as soon I applied around a hundredth of the force needed to tip over a a normal one.

The above examples avoid silly wording. But they are overly accurate: my hand's estimate of the force applied is nowhere near the accuracy implied by the numbers like a tenth and a hundredth.


My intuition is that a convention must already exist for this, perhaps in the field of health and safety to describe how much resistance/support a barrier is supposed to provide? As you can hopefully see, I only need to provide an indication of the order of magnitude.

A measurement in absolute terms would be great, but a nicely worded description in relative terms will also be enough.

Another area where this problem might be common is the specification of adhesive products (we do indeed use builder's grab adhesive to install our devices). Something like "glue 1 will hold the weight of a person, but glue 2 will only hold the weight of an A4 clip-frame".

In an ideal world we would have categories or an agreed system with three levels of stability, where everybody knows what level 1/2/3 is. I'm afraid I'm probably not important enough to try and establish any such categories though. I am hoping that this problem has been resolved in one industry or another and there is a solution I can adopt.

Finally I am conscious this question can be seen as opinion based. If more people think this is an issue please let me know and I will try to edit my question to make it more appropriate for stack exchange.

I am also unsure I am posting on the right site: I tried to apply tags like amateur, communication, engineering and none of these exist. Naturally please let me know if you can think of a more suitable site, but I think my problem is fundamentally about communication in physics.

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  • $\begingroup$ You may have better feedback from engineering.stackexchange.com $\endgroup$ Sep 22 '20 at 1:30
  • $\begingroup$ Make sure to give a description of the dimensions and "foot print" of the objects that you are using for your examples. $\endgroup$ Sep 22 '20 at 1:42
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If you are creating an engineering report that gives acceptance standards, you need to use numbers. You are right. Your examples are totally unsuitable for a professional report.

You are trying to establish standards where something is acceptable or not. There can be no ambiguity. Pushing hard enough to tip some washing machine over will be different if you have a heavy or light washing machine, a waxed floor, push near the bottom or top. This can create disagreements where one person says it is acceptable and another does not.

The numbers you want are torques if you are talking about the effort needed to tip over something, and forces if you are talking about sliding it.

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