A rectangular steel bar shown is fixed at the right end has a thickness of 20 mm. The temperature is increased by 20C and a force F is applied as shown midway along the bar. Use the properties E=200 GPa, a=12(10^-6)/C. (a) Determine the value of the force F which results in zero displacement at the left end (x=0mm) . For the value of force F determined in part (a) and the temperature rise of 20C, determine the following: (b) the stress at x=50mm, (c) the displacement at x=100mm , and (d) the stress at x=150mm .