Question 6.S&C.9: 1. Is there a buoyant force acting on you? If there is, why ...

1. There is a buoyant force acting on you, and you are buoyed upward by it. You aren’t aware of it only because your weight is so much greater.

2. If the balloon is free to expand as it rises, its increase in volume is counteracted by a decrease in the density of higher-altitude air. So, interestingly, the greater volume of displaced air doesn’t weigh more, and buoyancy stays the same. If a balloon is not free to expand, buoyancy will decrease as a balloon rises because of the less dense displaced air. Usually balloons expand when they initially rise, and if they don’t eventually rupture, fabric stretching reaches a maximum and balloons settle at an altitude where buoyancy matches weight.