If you live in a city your stove can be powered by natural gas. This gas is mainly methane gas and has a density of about 0.72 kilograms per cubic meter. What minimum sized balloon would you have to fill in order to be able to be lifted into the air? Take your mass to be 75 kilograms and the temperature of the outside air to be 20 degrees C. Neglect the mass of the balloon rubber and assume that the balloon is spherical in shape.
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