1. The problem statement, all variables and given/known data The temperatur at the point (x,y,z) in a substance with conductivity K=6.5 is u(x,y,z)=2y2+2z2. Find the rate of heat flow inward across the cylindrical surface y2+z2=6, 0≤x≤4. 2. Relevant equations F=-k∇u -k∫∫s∇u*ds 3. The attempt at a solution So F=-6.5(0,4y,4z) I get lost with how to find n because it is not in the usual cylindrical form x2+y2=6. Please give me some guidance. Thank you.