Topics Gas . Buoyancy Description Experiment with a helium balloon, a hot air balloon, or a rigid sphere filled with different gases. Discover what makes some balloons float and others sink. Learning Objectives . Determine what causes the balloon, rigid sphere, and helium balloon to rise up or fall down in the box. . Predict how changing a variable among P, V, T, and number influences the motion of the balloons.3. Click on "Layer Tool" Compare the pressure at the bottom and top of the chamber. Which is higher? 4. Adjust the gravity so that it is significantly higher. a. Describe what happens to the particles. b. Use the layer tool to compare pressures at the bottom and the top. Is the difference smaller than in question 3