1.A balloon is to be used to carry meteorological instruments to an elevation of 15,000 ft where the air pressure is 8.1 psia. The balloon is to be ?lled with helium, and the material from which it is to be fabricated weighs 0.01 lbf/ft^2. If the instruments weigh 8 lbf, what diameter should the spherical balloon have?
2.A steel I beam is supported by a pin at point A and a rocker at B, and a cable applies a 2000lb force. The beam is uniform and weighs 26 lb/ft. Determine the support reactions.