# “The monofilament wire has a tensile strength of 18 kg” What does this mean?

I am used to strength being measured in units of stress, such as pounds per square inch, or Pascals.

I am assuming what the author is trying to say is, "this filament will break when holding 18 kg," is that correct?

## 1 Answer

Material strength is generally expressed in the form of stress but for a component using a load is perfectly logical. Equally while using Newtons would be more precise quoting an ultimate load as a mass is often more practically useful.

What is less clear is whether this is a 'safe working load' (ie you can hang a mass of 18kg off it and it won't break) or if it is the ultimate load.

Safe working loads generally include a factor of safety to account for dynamic loading and quoting the load in kg rather than N sort of implies this but assuming 18kgf as the breaking load would be more conservative in the absence of any other information.

• Thank you for your response. Would it be correct to say 18 kg of mass weighs 18 kgf? I am a bit unfamiliar with kgf. – Evan Oct 25 '17 at 22:30
• Yes, exactly kgf is kilogram force ie the weight of a kg in earths gravity. Essentially it is a way to lump together mass and weight in circumstances where the precise difference in definition doesn't matter. – Chris Johns Oct 25 '17 at 22:43