Introduction to the Acrylic tube: Demonstrates inflating air into the large tube, the pressure inside the tube increases, the gas enclosed in the small tube is compressed, and the water in the large tube transfers to the small tube, causing the liquid level in the small tube to rise. The weight increases and it begins to sink. Stop inflating, the pressure in the large tube decreases, the gas volume in the small tube increases, the buoyancy increases, and the small tube surfaces.