Flashcards for Python lesson 8: Forces and integration
Read the front, say the back to yourself, then open the card.
Gravity on body i
Σ G·mⱼ·(rⱼ − rᵢ) / |rⱼ − rᵢ|³ over the other bodies j.
Leapfrog
Half a velocity step, a whole position step, another half velocity step.
Periodic orbit
A start that comes back exactly to itself after one period.
Centre of mass
The average position weighted by mass; it moves only if the total momentum is not zero.
Chaos
The tiniest change at the start grows until the motion is completely different.