Quote (cky24 @ Feb 28 2014 11:57pm)
The area is just the cross-sectional area, which is just the area of a circle since CD is a pipe and the diameter is given.
Area of a circle using the diameter is [(pi/4) * (d^2)]
Area of a circle using the radius is [(pi) * (r^2)]
The answer will be in MPa
Pa = Newtons per meter squared (N/m^2)
M = mega = 10^6
G = giga = 10^9
(on your calculator you'll probably get an answer to the seventh power, for example, 1.24623452345 *10^7 Pa would just be 12.46 MPa or 0.0125 GPa)
Need to find both the x and y reaction at B because you need the resultant force at B, not just the x or y.
http://i57.tinypic.com/j66fjl.jpg
These problems you always start with statics to find your forces in the members the question is looking for, unless of course the forces are already given. Hanging members like a truss hanging from the side of a wall, you'll want to find reactions at the pins and other supporting members. Problems with ropes in tension you'll want to find the force in the rope, etc, etc. If you were good at statics, starting these problems won't be an issue because all you need to find is the forces and from there it's just plugging things into the equations.
Average Normal Stress equation is, sigma = (P/A)
Average Shear Stress equation is, tau = (V/A)
A = cross-sectional area of the member DC which is (pi*r^2) if you use the radius or (pi/4)*(d^2) if you use the diameter.
P = the force in member DC after using statics
V = the shear force of the pin, which is going to be P/2 at B (look at my little FBD as to why).
nice im surprised u did it for him lol