5. A balloon filled with helium at the atmospheric pressure po occupying volume V, when released rises up and bursts at an altitude where atmospheric pressure is 0.5po. Immediately before bursting, the balloon has a volume of 1.25 V. If rubber used in making the balloon has mass m and density p, find breaking stress of the rubber. Assume the balloon always spherical in shape, the density of the rubber constant and temperature outside uniform and constant. 9 PoVP Tom