A steel rotating-beam test specimen has an ultimate strength, Sut, of 1600 MPa (232 kpsi). Estimate the life of the specimen if it is tested at a completely reversed stress amplitude, σrev, of 925 MPa. Take the value of the fatigue strength fraction, f to be 0.77.

Asolid cylinder is concentric with a straight pipe. the cylinder is 0.5 m long and has an outside diameter of 8 cm. the pipe has an inside diameter of 8.5 cm. the annulus between the cylinder ad the pipe contains stationary oil. the oil has a specific gravity of 0.92 and a kinematic viscosity of 5.57 x 10-4 m2/s. most nearly, what is the force needed to move the cylinder along the pipe at a constant velocity of 1 m/s?