posted by Bobby .
An aluminum bar has the desired length when at 10 degrees Celsius. How much stress is required to keep it at this length if the temperature increases to 33 degrees Celsius?
The change in L = (Initial L)x(Force)/E/Area.
The change in L also = (Alpha)x(Initial L)x(Change in Temperature)
So, (Alpha)x(Change in Temperature)x(E) = Force/Area
So, (25x10^-6)x(23)x(70x10^9) = 4.0x10^7 N/m^2