# shear force at boundary

We all know that $$\tau = VQ/ It$$ how to determine the shear stress at G ? I'm having problem of finding Ay centroid if the solid that i found earlier is y = 98.5mm

so , my working is Q = Ay = (250x10^-3)(50x10^-3)( 50+125-98)(10^-3) = 9.63x10^-4

I'm considering the area above the G .

Is my concept correct ? edited : There's a dashed line from G to the bottom . It's making me confused . for Q , should i consider the area either to the left or right of the G ?

## 1 Answer

If you want to approximately find it, you probably need the dashed line part too, else it's like having being on the edge where shear is 0.

Any way, this is not the proper way of doing so. Take a look at this which is similar: Interpretation of shear flow/shear center of L-profile

• If this is not the proper way of doing it, please edit your answer to describe how it should be done. – Wasabi Jan 9 '19 at 22:52
• The link of a dublicate post serves this purpose. – Apostolos Grammatopoulos Jan 9 '19 at 23:06
• How so? That link is about shear flow, while this question is about shear stress (they aren't the same, of course). Also, if you believe that link is a sufficient answer to this question, you should flag this question as a duplicate of that one instead of adding a link-only answer (as per standard SE policy, though I don't believe that's the case here). Or at least edit your answer to make it stand alone, leaving that link as a reference. – Wasabi Jan 9 '19 at 23:36