Jia-Hui and Chukwudi are standing in an empty swimming pool. Jia-Hui is wearing a party balloon on a string around her wrist, and Chukwudi is holding an inflated beach ball. They both let go of their items at the same time. What happens to the balloon and the beach ball? Respond very briefly.
The balloon rises and the beach ball falls to the ground of the pool. The balloon rises because it is filled with a gas that is lighter than air, likely helium, which makes it buoyant and causes it to float upwards. On the other hand, the beach ball falls due to gravity. Despite being filled with air, it does not have sufficient lift to overcome the gravitational pull because the air inside the beach ball is not significantly less dense than the surrounding air.