• Question: How do you test for the mass of a balloon?

    Asked by 374evoa44 to Anthea, Chloe, Kevin, Michel, Sean on 14 Nov 2014.
    • Photo: Chloe Kinsella

      Chloe Kinsella answered on 14 Nov 2014:

      Is the balloon empty? Filled with air? Or filled with helium? You can weigh an empty balloon or a balloon filled with air to get its mass. But a balloon filled with helium is a bit trickier. It will be so light that it wont stay on a scales, it will keep floating upwards. A helium balloon has two opposing forces acting on it: gravity pulling it down, and buoyancy pushing it up. Buoyancy wins, so you can’t really weigh this balloon, even though it does have mass.
      Think of it this way: If you could put a balloon with five grams of helium in it in a vacuum chamber, then there’d be no buoyancy force pushing it up. Only gravity acts on it, so if it sat on a scale it would register as five grams!

    • Photo: Kevin Healy

      Kevin Healy answered on 14 Nov 2014:

      Bring it to space and see how hard it is to push the bollon! By putting it in a vacuum you dont need to worry about it flying off and by seeing how hard it is to push you can calulate the mass using Mass = Acceleration(how fast it speeded up when you pushed it)/Force(how hard you pushed it).
      You could also just empty out the air but you woudnt get to go to space then!

Comments