You are growing two different types of bacteria. The bacteria have a maximum doubling time of 1.35 hours (cell 1) and 0.25 hours (cell 2), respectively. You are growing them in a nutrient rich batch-reactor with the maximum growth rate. If you seeded the same amount of bacteria in the reactor 1) What would be the ratio of cell 1 concentration /cell 2 concentration after 10 hours of growth? 2) How long will it take for cell 2 concentration to be 10 times of cell 1 concentration?

Steel is coated with a thin layer of ceramic to protect against corrosion. what do you expect to happen to the coating when the temperature of the steel is increased significantly? explain.

Fluids at rest possess no flow energy. a)- true b)- false

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?