Optional Practical: Orbit simulation (Algodoo)
When a body is in a circular orbit round another one the centripetal force required for the circular motion is provided by the gravitational attraction, by equating these terms we can find a value for the speed,v of the orbit.
Setting up the simulation
In reality the value of G is 6.67 x 10-11 Nm2kg-2 this means that orbits around low mass objects would be very slow, In Algodoo you can vary the gravitational constant to speed things up a bit.
- Open a new scene and show the grid
- Draw a circle, double click it and from materials give it a mass of 1000 kg and an attraction of 0.04 Nm2kg-2 (this is G).
- Place a second smaller circle 10 m to the right of the first one and give it a mass of 0.005 kg
- Calculate the speed necessary to put the smaller mass in orbit set the velocity using the "velocities" options.
- Double click the orbiter (pause first) and display the information. You can make this stay in view by dragging the window to one side.
- Observe the values for KE, PE and total energy as the body orbits.
- Observe what happens if you change the velocity of the orbiter.
- Observe the effect of adding a small amount of air resistance (note the changes in energy)
- Try adjusting the "attraction". Observe the changes in energy, try to keep the orbiter in orbit.
- Set the large mass to 500 kg and calculate the radius and speed for a circular orbit. Try this out to see if you are right.
- Make a mini solar system with several "planets".
- See if you can put a moon in orbit around a planet.
- Try putting a 500 kg mass in orbit round another 500 kg mass.
- Cover the surface of a planet with water and observe the tidal effect as a moon orbits.