# Trying to make sense of the strength to weight ratio

## Main Question or Discussion Point

I need some help with something that seems rather simple, but I don't know how to apply the formula. Let's say I have a table and based on the particular material from which it is constructed, it has a strength to weight ratio of 50 kN·m/kg. If I were to place an object on the table that weighed 50 kg, would I be able to use the strength to weight ratio to determine if the table is strong enough to support it?

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DaveC426913
Gold Member
I do not think so - but I am no expert.

The StW ratio of a table is highly dependent on the construction of the table.

A useful StW ratio will be figured under specific conditions. For example, a beam of dimensions l x w x d made of steel will have a different StW of a comparable beam made of balsa.

You can use that simple calculation to decide - in conjunction with engineering principles - to figure out how to make the table to support a given weight.

Is that value for the material or for the table?
Usually it is used as a material (and not object) property. I don't see how will be useful for an object.

Even though is sometimes called strength-to-weight ratio, the usual meaning is that of the ration between the strength (in Pa or N/m2) and density (kg/m3).
So it has nothing to do with the weight supported by an object made from this material.
It is useful when you need to design something as light as possible for a given load or strength.

For your question the strength will be all you need. I mean as material parameter. You need a lot of engineering experience (which I don't have). :)

CWatters