Solve each of the following problems with the trial solution method. Identify the free, forced, transient, and steady-state responses.
a. x¨ + 8x˙ + 15x = 30 x(0) = 10 x˙(0) = 4
b. x¨ + 10x˙ + 25x = 75 x(0) = 10 x˙(0) = 4
c. x¨ + 25x = 100 x(0) = 10 x˙(0) = 4
d. x¨ + 8x˙ + 65x = 130 x(0) = 10 x˙(0) = 4

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?

The filament of an incandescent lamp has a temperature of 2000k. calculate the fraction of radiation emitted in the visible light band if the filament is approximated as blackbody

The thermal expansion or contraction of a given metal is a function of the f a)-density b)-initial temperature c)- temperature difference d)- linear coefficient of thermal expansion e)- final temperature f)- original length