Orbital Speed
Orbital Speed is a free interactive simulation of circular orbital motion for GCSE Physics (Edexcel IGCSE 4PH1, spec point 8.6). Students time an orbiting body, read off its orbital radius, and calculate its speed to investigate how orbital speed changes with orbit radius. No login required.
Aim: To investigate whether bodies in larger orbits move faster or slower.
Orbital Radius
Stopwatch
0.0sim-days
Data Table
| # | Radius, r (million km) | Period, T (sim-days) | Your speed, v (km/s) | Check |
|---|
- Start with the Earth preset (150 million km).
- Click Start Timer the instant the planet crosses the dashed marker line at the top of its orbit.
- Click Stop Timer the next time it crosses that same line, after one complete orbit. This is your period, T.
- Click Record Reading to log r and T in the table, then calculate the orbital speed v = 2πr ÷ T yourself (convert million km to km, and sim-days to seconds) and type it into the table to check your answer.
- Repeat for at least four different radii spanning the full range of the slider.
- Look at your table: as the orbital radius increases, does the orbital speed increase or decrease?