The Coolest Part of Physics
This was the first project we have done with Dr. Drew as our Math/Physics teacher and it was a really great experience. Like our "Team Name Campaign" project, we chose a subject that we found interesting and then we tried to "sell" it to our classmates. We did this by showing them all how cool it was. To do this we had to fully understand the concept and then create a presentation for the class. My group, (Samantha Salazar, Tressa Thompson and myself), chose Hot Air balloons to represent as the coolest part of physics.
Understanding Buoyancy
Buoyancy
A solid object will sink in a fluid if its density is greater than the fluid’s density, and will float if its density is smaller.
Hot Air
The force of air pressure on an object depends on how often air particles collide with that object, as well as the force of each collision. We saw that we can increase overall pressure in two ways:
So, to lower air density in a balloon without losing air pressure, you simply need to increase the speed of the air particles. You can do this very easily by heating the air. The air particles absorb the heat energy and become more excited. This makes them move faster, which means they collide with a surface more often, and with greater force.
For this reason, hot air exerts greater air pressure per particle than cold air, so you don't need as many air particles to build to the same pressure level. So a hot air balloon rises because it is filled with hot, less dense air and is surrounded by colder, more dense air.
A solid object will sink in a fluid if its density is greater than the fluid’s density, and will float if its density is smaller.
Hot Air
The force of air pressure on an object depends on how often air particles collide with that object, as well as the force of each collision. We saw that we can increase overall pressure in two ways:
- Increase the number of air particles so there is a greater number of particle impacts over a given surface area.
- Increase the speed of the particles so that the particles hit an area more often and each particle collides with greater force.
So, to lower air density in a balloon without losing air pressure, you simply need to increase the speed of the air particles. You can do this very easily by heating the air. The air particles absorb the heat energy and become more excited. This makes them move faster, which means they collide with a surface more often, and with greater force.
For this reason, hot air exerts greater air pressure per particle than cold air, so you don't need as many air particles to build to the same pressure level. So a hot air balloon rises because it is filled with hot, less dense air and is surrounded by colder, more dense air.
Why Is It Cool?
We think that buoyancy is the coolest part of physics because it is seen everywhere in the world, all of the time. We see buoyancy in helium every time a balloon is floating in the air. When a hot air balloon is overhead and even when a boat passes by in the water. We found this especially interesting due to the large size and astonishing amount of cargo that is carried across the water on boats today. A major question was, "How do such heavy things float in water?", and now we have the answer to that. Basically, what may not seem possible at first glance, is later proven through scientific concepts.