Which of the following best describes the role of engineers

20. Of these four materials used as a dielectric, which is the best insulator? a. Pure water C. Glass b. Petroleum d. Air

Can the Diesel engine afford to have a large compression ratio? Why?

Oil (SAE 30) at 15.6 oC flows steadily between fixed, horizontal, parallel plates. The pressure drop per unit length along the channel is 35 kPa/m, and the distance between the plates is 9 mm. The flow is laminar.

You get invited to a party at a 1,200 sf apartment, where there are a total of 23 people. The apartment has ceilings that are 8 ft above the floor. Three people begin smoking 2 cigarettes per hour each.

A liquid refrigerant (sg=1,2) is flowing at a weight flow rate of 20,9 N/h. Refrigerant flashes into a vapor and its specific weight become 11,5 N/m^3. If the weigt flow rate remains at 20,9 N/h, compute the volume flow rate[10^-4 m^3/sec].

A completely reversible heat pump produces heat at a rate of 100 kW to warm a house maintained at 25℃. The exterior air, which is at 0℃, serves as the source.

A closed system undergoes a process in which work is done on the system and the heat transfer Q occurs only at temperature Tb. For each case, determine whether the entropy change of the system is positive, negative, zero, or indeterminate.

A scientist who is evaluating an ancient human skeleton for signs of vitamin and nutrient deficiency is conducting:

Which of the following is required in order to make a protected left turn A. A left green arrow B. No oncoming traffic C. A left turn only lane D. A large enough gap

At steady state, a cycle develops a power output of 10 kW for heat addition at a rate of 10 kJ per cycle of operation from a source at 1500 K. Energy is rejected by heat transfer to cooling water at 300 K.