+1313 The formula is ... Q=k*(T2-T3)/x.
Q=0.7*(26-T2)/0.15
Q=0.45*(T2-T3)/0.09
Q=0.7*(T2-4)/0.15.
Transpose to be in matrix form. It's staring at me in the face (at 3am.) Good night. Hope to solve this for a PBL report by today.
Please also verify, given the equation above (for Energy conductivity) that R=the thickness of a body engery (Q) conducts through (divided by) the thermal conductivity, aka R=T/k?
Is it easier to use derivative for this (it's still Fouriers law right? Or is it a derived formula/new formula?... I should google this but yeh .. bed time. thanks for the help.
+1313 Or really. I thought the lecturer just wanted to resolve using two equations. Though taking the inverse of a 3x2 matrix might not have been posible right? Hope I can transpose it now, knowing what i want to achieve. I wouldn't have known to invole Q and tbh I don't know why but I was just confused about how to transpose it. I think that it is an area for development this weekend to be honest and next week with Maths stupports. Really exceptional and I will do the rest.
+33616 If you take the first and the third equation you have 2 simultaneous equations in the 2 unknowns, Q and T2, so you could solve for them, then insert the values into the middle equation to get T3. Perhaps that is what your lecturer wants you to do.
+1313 You way will be nicest solve. No point dancing around the bush now. Getting to the neatest solution is always more benificial and makes life easier. I meant literally dancing around a bush wasting time going backwards to do that way. Should be bonus marks not less marks if solved with a 3x3 and in one go. lol.
+1313 Working on this I solved the determinant from the top for and determinant of the other 2x2. Doing this the scalar in colomn 3 is a 0. What do I do? It makes the whole equation 0 right? Should I have soved with the second column?
+1313 Can anyone assit me with this. I cannot get the answer Alan posted. It's due in the morning and it's late. Thanks. Please post something to assit me. I have
Can someone help with the determinant , and solving the inverse. I am not able to solve it correctly which is confusing me as to why. I should be able to.
+128631 So you want the determinant for this??
0.15 0.7 0
0.09 -0.45 .45
0.15 -0.7 0
Recopy the first two columns
0.15 0.7 0 0.15 0.7
0.09 -0.45 0.45 0.09 -0.45
0.15 -0.7 0 0.15 -0.7
Then....just use the "trick" of multiplying and subtracting the diagonals....there are only two multiplications necessary!!......so we have
[0.7 * 0.45 * 0.15] - [-0.7 * 0.45 * .15] = .0945
I'll look at getting the inverse for you.......if I can!!
(I assume that you cannot just use some CAS to do this with??)
+33616 Stu, if you use the results I provided here: http://web2.0calc.com/questions/inverse-matrices_1 you should be able to calculate the inverse ok.
However, I don't think you should expect better marks for solving it as a 3x3 rather than as a 2x2 plus a substitution. The latter is easier and I'm a great believer in the KISS principle (Keep It Simple Stupid! Or in your case, perhaps: Keep It Simple Stu!)
