Zenobia is standing on the ground holding a helium-filled balloon on a string. If Zenobia releases the string, what happens to the balloon and why? Provide a very short response.
The balloon ascends into the air. This happens because the helium inside the balloon is less dense than the surrounding air, providing the balloon with buoyancy, which is a force that pushes it upwards against the pull of gravity. Since Zenobia is no longer holding it down, this buoyancy allows the balloon to rise.