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.

Ariver flows from north to south at 8 km/h. a boat is to cross this river from west to east at a speed of 20 km/h (speed of the boat with respect to the earth/ground). at what angle (in degrees) must the boat be pointed upstream such that it will proceed directly across the river (hint: find the speed of the boat with respect to water/river)? a 288 b. 21.8 c. 326 d. 30.2