Problem 1 The motor mounted on the bracket is acted on by its 160N weight and its shaft resists a repeated thrust load of 120N and a repeated couple of 25N.m that are applied to it. If the motor is fixed to the bracket by four bolts and the stress concentration factors for shear stress is 2.5 and for normal and bending stresses are 2.1, determine the diameter of the bolts for a static and fatigue factor of safeties that are more than 4. Note that: a. The horizontal distance between the bolts and the shaft's axis is 100mm and the endurance limit is 129MPa b. Choose the diameter of the bolts from Metric Mechanical-Property class 25 N-m 120 N 100 mm 200 mm -75 mm 160 N Problem 2 The motor in problem one supposes to have a bearing inside it. Take (n/L,n,)-400, a reliability goal of 0.99, and an application factor of 1.5, select a suitable angular contact ball bearing for the motor.