Workshop › Lunar Lander › Step 9 of 31

Moon gravity

What we are doing

On the moon gravity is weak: every frame it adds a little to the falling speed, so the lander drifts down slowly and speeds up.

```js
let gravity

  gravity = 0.025

  lander.vy += gravity
```

What it means

• gravity is added to vy every frame, before the lander moves.
• After 10 frames vy is 0.25; the lander has fallen 0.025 × (1 + 2 + ... + 10) pixels.

Your turn

1. Under let lander write let gravity.
2. In reset, under the lander line, write gravity = 0.025.
3. In update, write lander.vy += gravity as the first line.

Skills: Velocity and gravity

← The game loop Around the sides →

All steps

1. Random hills
2. Draw the hills
3. A landing pad
4. The height at any x
5. The lander
6. Draw it around its own middle
7. Two feet
8. The game loop
9. Moon gravity
10. Around the sides
11. Flying or not
12. Touching the ground
13. Remember held keys
14. Tilt
15. The engine
16. A flickering flame
17. Fuel
18. Touch controls
19. Landing or crashing
20. Fly again
21. Landed or crashed?
22. Readouts
23. Levels
24. Score
25. Next level or new game
26. A narrower pad
27. A high score
28. Burst into pieces
29. Pieces fall and fade
30. Draw the wreck
31. Build it yourself: wind