A rigid block has a weight W and is supported by two steel posts (A and B in Figure 1) and a brass post (C in Figure 1), as shown. The posts all have the same original length 2 m and cross-sectional area A = 4000 mm². 

Two strain gauges are bonded to the outer surface of each steel post and coupled in half-bridge configuration into arm 2 and arm 4 of a Wheatstone bridge.

The strain gauge factor for the strain gauge on post A is 1.9, while that on post B is 2.0.

When the temperature of the brass post C is raised by 10 °C, the Wheatstone bridge output (Vo/Vi) is 146 x10^-6 V/V.

1.1 Calculate the stress in the steel posts at this point.