During its fi nal approach to the runway, the aircraft speed is reduced from 300 km∕ h at A to 200 km∕ h at B.
Determine the net external aerodynamic force R which
acts on the 200-Mg aircraft during this interval, and fi nd
the components of this force which are parallel to and
normal to the fl ight path

Ahe-xe mixture containing a 0.75 mole fraction of helium is used for cooling electronics in an avionics application. at a temperature of 300 k and atmospheric pressure, calculate the mass fraction of helium and the mass density, molar concentration and molecular weight of the mixture. if the cooling capacity is 10 l, what is the mass of the coolant?