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 / m2 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 m1/2. However, if it is, I still don't know what m is as a unit. In other words I know m2 is - square meters.