31.A satisfactory radiograph is produced as follows: Single phase-2 pulse, 80kVp, 25 mAs, 72inch SID, 12:1 grid, 200 RSV. A new radiograph is to be produced with the following changes: 3-Phase-12 pulse, 68kVp, 8:1 grid, and 400 RSV. What changes should be made to maintain the original density?

The mass flow rate of the fluid remains constant in all steady flow process. a)- true b)- false

The temperature of air decreases as it is compressed by an adiabatic compressor. a)- true b)- false

Apipe with an outside diameter of 15 cm is exposed to an ambient air and surrounding temperature of -20°c. the pipe has an outer surface temperature of 65°c and an emissivity of 0.85. if the rate of heat loss from the pipe surface is 0.95 kw per meter of length, the external convective heat transfer coefficient (h) is: (a) 12.5 w/m"k (b) 18.6 w/mk (c) 23.7 w/mk (d) 27.9 w/mk (e) 33.5 w/mk