You are designing an antenna to be suspended from a helicopter. the diameter of the antenna is 12 inches. the maximum speed of the helicopter is 200ft/s. what must the design goal natural frequency of the antenna be if the design goal natural frequency is to twice that of the vortex shedding frequency? for units of frequency use radians s be ec. assume a strouhal number of 1.257

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