hot air balloon

The exhibit is a hot air balloon that can be lifted into the air with a vertical sling. Click the ignition button to heat the air inside the hot air balloon through the heat source. The air volume expands, and some of the gas inside the balloon is expelled. The density of the air inside the balloon decreases, and the gravity of the hot air balloon decreases. Due to the constant buoyancy from the surrounding air, the buoyancy is greater than its own gravity, and the hot air balloon rises. When the hot air balloon rises to its highest point, the air inside slowly cools down and its volume decreases, allowing external air to enter the balloon. The air density inside the balloon increases, and the overall gravity of the hot air balloon increases. However, the buoyancy of the air remains unchanged and is less than gravity. Eventually, the hot air balloon falls back onto the launch platform.

The unit is designed for unsupervised public use: controls are recessed or shielded, moving parts are enclosed, and the interface is operable by a child of about six with no instruction. Where a screen is used, the language can be switched without changing the hardware, and the content can be replaced on site.