A 1Kg non-stretched balloon fabric on the ground (P0= 1 bar) is attched to a 2Kg payload. One Kg of helium is places in the balloon. How many pounds of restraint are needed to keep the assembly tethered to the ground? When the restraints are cut how high does the assembly go in as isothermal atmosphere at -10C? The balloon fabric ca inflate to a maximum radius of 5 meters. WHy does the balloon stop rising when it reaches maximum inflation? What is the pressure of helium inside the balloon when it reaches maximum inflation? If a little helium is released will the balloon go up or down?