Question: A straight deformable bar of cross-sectional area A= 25 mm2 , length l= 100 cm, mass density t = 7800 kg/m3 , Young's modulus E = 2.1 # 1011 N/m2 , a Poisson's ratio n = 0.3 is anchored at one end and subjected to a sinusoidal axial load of unknown amplitude and frequency ~ = 45000 rad/s at the other end. Disposing of three identical strain gauges (Kg = 2.3) that can be attached to the bar and connected in a Wheatstone bridge (vi = 30 V), determine the force amplitude when the maximum output voltage of the bridge is 2.5 # 10-6 V. Consider the system is lossless.