Forced air at t[infinity] = 25°c and v = 10 m/s is used to cool electronic elements on a circuit board. one such element is a chip, 4 mm × 4 mm, located 120 mm from the leading edge of the board. experiments have revealed that flow over the board is disturbed by the elements and that convection heat transfer is correlated by an expression of the form

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

At 12 noon, the count in a bacteria culture was 400; at 4: 00 pm the count was 1200 let p(t) denote the bacteria cou population growth law. find: (a) an expression for the bacteria count at any time t (b) the bacteria count at 10 am. (c) the time required for the bacteria count to reach 1800.

An ideal otto cycle with air as the working fluid has a compression ratio of 8. the minimum and maximum temperatures in the cycle are 300 k and 1340 k. use constant specific heats at room temperature to determine (a) the amount of heat transferred to the air during the heat- addition kj/kg, (b) the thermal efficiency, and (c) the thermal efficiency of a carnot cycle ope limits. process, in rating between the same temperature