A steel bolt has a modulus of 207 GPa. It holds two rigid plates together at a high temperature under conditions where the creep of the steel is described by the equation:ε=ε0σσ0nwhere n= 3, andε=127.8 10−×/s when σ= 28 MPa. The bolt is initially tightened to a stress of 69 MPa. What is the stress in it after 1 year? (14 MPa)

The higher the astm grain size number, the finer the gran is. a)-true b)-false

Athin walled concentric tube exchanger is used to cool engine oil from 160°c to 60°c with water that is available at 25°c acting as a coolant. the oil and water flow rates are each at 2 kg/s, and the diameter of the inner tube is 0.5 m and the corresponding value of the overall heat transfer coefficient is 250 w/m2. oc. how long must the heat exchanger be to accomplish the desired cooling? cpwater=4.187 kj/kg-candcpengine el=2.035 kj/kg·°c, oil . 120]

Air is compressed isentropically from an initial state of 300 k and 101 kpa to a final temperature of 1000 k. determine the final pressure using the following approaches: (a) approximate analysis (using properties at the average temperature) (b) exact analysis