A4-kg sphere rests on the smooth parabolic surface.
determinethe normal force it exerts on the surface and the mass mb
of blockb needed to hold it in the equilibrium position
shown.

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?