About
The buoyant force (Fl) of the aerostatic baloon is obtained by heating air inside its cavity. The buotant force is due to the difference of density between the hot air inside and the cold air outside the balloon cavity. The buoyant force compensate the balloon weigth (w) (having into account the ballast (wl ) and people weight).
The following assumptions have been made in the model:
- The air is a perfect gas. Therefore air density can be computed with the following equation : density=P/R*M /T. Where R is the constant of ideal gases, M is the molecular weigth of the air, P is the air pressure and T the air temperature.
- The standard atmosphere model from the surface to 11 km altitude is used to describe the variations of the temperature and pressure with altitude. This model states that the temperature decreases 6.5 K per Km (T=T0-6.5K/Km*h(km)) and the pressure follows the following equation: P=P0*(T0/T(h))^-5.256. Where T0 and P0 are the temperature and pressure at sea level.
Dpto. de Informática y Automática
E.T.S. de Ingeniería Informática, UNED
Juan del Rosal 16, 28040 Madrid, Spain
Translations
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Credits
Carla Martn; Tan Wei Chiong; Loo Kang Wee
Sample Learning Goals
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For Teachers Aerostatic Balloon
This simulation demonstrates Archimedes' Principle with a hot air balloon. The rising and falling of the hot air balloon is affected by the ambient temperature T0, the initial air pressure P0, and the mass of the hot air balloon m.
The left graph of the simulation shows the actual hot air balloon. The right graph plots the graph of pressure (blue) and height (green) against time.
Turning on the burner causes the hot air balloon to rise, turning the burner off causes it to descend.
Research
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Video
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Version:
- http://weelookang.blogspot.com/2018/05/hot-air-balloon-javascript-simulation.html
- http://www.euclides.dia.uned.es/simulab-pfp/curso_online/cap7_caseStudies/sec_balloon.htm by Alfonso Urquia and Carla Martin-Villalba
Other Resources
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Frequently Asked Questions: Hot Air Balloon Simulation
What is the purpose of the Hot Air Balloon JavaScript Simulation Applet?
This virtual lab is designed to illustrate how an aerostatic balloon operates. It serves as a practical demonstration of Archimedes' principle, showing how a hot air balloon can rise and fall by manipulating the buoyant force.
How does a hot air balloon generate buoyant force in this simulation?
The buoyant force is created by heating the air inside the balloon's cavity. This heating reduces the density of the air within the balloon compared to the cooler, denser air outside. The difference in density results in an upward buoyant force, as explained by Archimedes' principle.
What physical principles are modeled in this simulation?
The simulation primarily models Archimedes' principle, the ideal gas law (used to calculate air density based on pressure and temperature), and a standard atmospheric model that describes how temperature and pressure change with altitude up to 11 km.
What are the key variables that affect the hot air balloon in the simulation?
The behavior of the hot air balloon is influenced by several factors that can be adjusted or observed in the simulation. These include the ambient temperature (T0), the initial air pressure (P0), and the total mass of the balloon (m), which includes the balloon itself, ballast, and people. The burner's operation (on or off) directly controls the temperature of the air inside the balloon, thus affecting its buoyancy.
How does the simulation model the change in atmospheric conditions with altitude?
The simulation incorporates a standard atmospheric model that assumes air temperature decreases linearly with altitude (6.5 K per kilometer) up to 11 km. It also models the decrease in air pressure with altitude according to a specific equation that depends on the temperature profile. These models provide a realistic environment for the balloon's operation at different heights.
What visual feedback does the simulation provide?
The simulation features a visual representation of a hot air balloon on the left side. On the right side, it includes a graph that plots pressure (blue line) and height (green line) against time, allowing users to observe how these parameters change as the simulation progresses.
How can users interact with the simulation to observe the hot air balloon's behavior?
Users can interact with the simulation by controlling the burner. Turning the burner on increases the temperature of the air inside the balloon, leading to a decrease in density and an increase in buoyant force, causing the balloon to rise. Turning the burner off allows the air inside to cool, increasing density and causing the balloon to descend as the buoyant force decreases.
Who are the creators and contributors to this Hot Air Balloon JavaScript Simulation Applet?
The simulation was authored by Carla Martín from the Dpto. de Informática y Automática, E.T.S. de Ingeniería Informática, UNED, Madrid, Spain. Credits also go to Tan Wei Chiong and Loo Kang Wee for their contributions.
- Details
- Written by Wei Chiong
- Parent Category: 02 Newtonian Mechanics
- Category: 06 Pressure
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