Jinhai is standing in a room with a helium balloon tied to a string in his hand. If Jinhai lets go of the string, what happens to the balloon and why? Respond very briefly.
When Jinhai lets go of the string, the balloon rises toward the ceiling. This occurs because the helium inside the balloon is less dense than the surrounding air. Due to buoyancy, which is a force that makes lighter objects float in a fluid or in air, the helium-filled balloon is pushed upwards by the denser air around it. As a consequence, the balloon will float upwards until it reaches the ceiling or another obstacle that prevents it from rising further.