Which of the following is not true about hydraulic systems?
a. over half of all system problems are traced directly back to the oil
b. fire-resistant fluid should be used in applications where human safety is of concern
c. hydraulic fluid must have good lubricity to prevent wear between closely fitted working parts
d. in hydraulic systems, the operating temperatures must be kept between 170°f and 180°f
e. none of the above

Consider a 1.2 meter high and 2 meter wide glass window whose thickness is 6 mm and thermal conductivity is 0.78 w/m °c. the room temperature is maintained at 24 °c, while the outdoor temperature is -5 °c. the convective heat transfer coefficients on the inner and outer surfaces of the window are 10 w/m2 °c and 25 w/m2 °c respectively. (a) draw the thermal resistance network, etermine the steady rate of heat transfer t e glass window (c) determine the temperature of the inner surface of the window