Go to HYPERLINK "http://phet.colorado.edu/simulations/sims.php?sim=Balloons_and_Buoyancy" http://phet.colorado.edu/simulations/sims.php?sim=Balloons_and_Buoyancy and click on Run Now.
Determine what factors make a hot air balloon or a helium balloon float
1. Why does a hot air balloon float even though it is so heavy?
Hot air balloons float because the buoyancy force of the hot air is more that the weight. Buoyancy occurs because the hot air has a lower density than the cooler outside air. This lower density air weighs less than the air it replaces and that difference is the buoyancy.
2. What makes balloons float when they are full of air but not float when they are deflated?
Balloons float when they are full of hot air because the hot air weighs less than the air that is in the chamber which results in a floating balloon.
3. Starting with a hot air balloon, figure out how to make the balloon float. What factors affect the balloon floating or sinking? Explain three of these factors and your understanding of why this works as it does.
When the air is heated in the balloon, it causes the balloon to rise. This is because hot air is less dense than warm. Over time, if no more hot air is pumped into the balloon, the air cools and so the balloon falls.
4. Move to the rigid hollow sphere. What does it mean that the sphere is “rigid?”
A rigid sphere refers to a sphere that possesses an impenetrable shell.
5. Play with the parameters of the simulation and get the sphere to float. How is the sphere floating similar to and different from the floating hot air balloon?
The sphere is similar to the hot air balloon in its bobbing motion when nothing is added to the system. However, when species are added to the inside of the sphere, the result ends with a sinking sphere. This is much different than the hot air balloon when a gas species was added to