Weather Balloon Model

In this problem a weather balloon is lifting a set of instruments. At some point in time, the instruments are released. At what point (time and distance) do the instruments cease traveling up and begin to fall back toward Earth? The students are asked to build this model after they have dealt with the force models.

 THE MODEL
 Vensim Version Vensim PLE Software Right-click to download the model Weather BalloonVensim STELLA Version isee Player Software Right-click to download the model

[Diagram Level | Equations Level | Graphs ] ```Balloon_Velocity(t) = Balloon_Velocity(t - dt) + (Velocity_change) * dt
INIT Balloon_Velocity = 0

Velocity_change = Acceleration
Instrument_position(t) = Instrument_position(t - dt) + (Change_in_position) * dt
INIT Instrument_position = 0

Change_in_position = Instrument_velocity
Instrument_velocity(t) = Instrument_velocity(t - dt) + (Change_in_velocity) * dt
INIT Instrument_velocity = 0

Change_in_velocity = IF TIME >= 10 THEN (-9.81) ELSE (Acceleration)
Weather_Balloon_Position(t) = Weather_Balloon_Position(t - dt) + (Velocity) * dt
INIT Weather_Balloon_Position = 0

Velocity = Balloon_Velocity
Acceleration = (Upward_force-Instrument_mass*9.81)/(Instrument_mass)
Instrument_mass = 5
Upward_force = 98
```
##### Time Specs Settings
Range: 0-30; dt = 1.0; Integration Method = Runge-Kutta 2 Home | Contact | Site Map | Search