E-CodeTwo-body orbit and Kepler's equation — a TI-84 Plus CE program
ORBIT is a TI-BASIC program for the TI-84 Plus CE. From periapsis radius and speed: semi-major axis, eccentricity, period, apoapsis, then position and speed at a time after periapsis by solving Kepler's equation.
What it asks for and what it shows
It asks for 3 values at its prompts. In the example below it shows A KM, ECC, T MIN, RA KM, R(T) KM, NU DEG, V(T).
Example run
One of its oracle test cases: “e = .42, 2000 s”. The inputs are typed in order, and the results are the values the case expects on the screen.
| Step | Value |
|---|---|
| You enter | |
| Input 1 | 7000 |
| Input 2 | 9 |
| Input 3 | 2000 |
| The screen shows | |
A KM= | 12120.73146 |
ECC= | 0.4224770987 |
T MIN= | 221.3364675 |
RA KM= | 17241.46293 |
R(T) KM= | 11045.84224 |
NU DEG= | 103.4886719 |
V(T)= | 6.267869804 |
How it's checked
6 test cases, each checked against an independent method. Replayed key by key on a virtual TI-84 Plus CE, they make 42 checks.
How E-Code checks every program
Run it or put it on your calculator
- Open the library in the TI-84 Plus CE calculator and pick “Two-body orbit and Kepler's equation” (ORBIT).
- Put it on your own calculator with a computer and a USB cable, or type it in by hand.
Related programs
- Projectile with air drag (RK4)
- Slider-crank kinematics
- Oblique central impact
- Block sliding onto a spring
- Rolling body on an incline
All TI-84 Plus CE physics programs · All TI-84 Plus CE programs