Work Step by Step
An inflated contains air at a higher pressure than the air around the balloon (because the inside air not only must fight the air pressure pushing in, but also resist the elastic balloon walls that want to pull inward). The higher-pressure air inside the balloon is denser than the air just outside the balloon, and its weight is greater than that of the volume of lower-density outside air that was displaced. In other words, Archimedes’s Principle tells us that the weight of the air inside the balloon exceeds the magnitude of the buoyant force on the balloon. An air-filled balloon weighs a bit more than an empty balloon when measured on a scale.