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## Main Question or Discussion Point

Hi. Stress is measured on Pascals. It's force divided by area. Area of course is m x m. So when stress is given it's in units of MN / m

Okay. I'm looking at something called the Hall Petch equation. There a constant in it labelled k.

In an example, k is given as 0.45 MN m

Does this make any sense or is there an error with the description of k?

I mean, what is m

P.S. Possible that there is an error in the text. And that k is MN m

_{2}or MN m^{-2}.Okay. I'm looking at something called the Hall Petch equation. There a constant in it labelled k.

In an example, k is given as 0.45 MN m

^{-3/2}Does this make any sense or is there an error with the description of k?

I mean, what is m

^{-3/2}? Thanks.P.S. Possible that there is an error in the text. And that k is MN m

^{1/2}. However, if it is, I still don't know what m is as a unit. In other words I know m^{2}is - square meters.
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