1. The problem statement, all variables and given/known data Why is an 'I' beam good at supporting loads? (Bear in mind that I'm only 16, so I haven't met moments of inertia or anything like that, but have met basic calculus) 3. The attempt at a solution Here's what I think so far. When a weight is placed on an I beam, the vertical part of the 'I' is very good at bearing the vertically downward force, and the flanges stops the beam from rotating. However if this is true, surely all you'd need is a thick solid beam which is relatively wide which could support the load itself and because of its width, wouldn't need to worry about twisting. However somewhere I read it has something to do with shear and bending forces, but I don't really understand what a shear force is and how it comes into it. If someone could explain it like this it would be really helpful Thanks.