Match the Beat
The server picks a world (the Moon, Mars, Earth or Jupiter), a release angle and a target for how long one full swing should take (always achievable), you set the length of the string, and a real pendulum model judges whether one swing takes that long. Hitting the beat refunds your run.
About this simulation
What it shows
A puzzle on a swinging pendulum: the world it hangs on (Moon, Mars, Earth or Jupiter) and the angle it is released from are given, along with a target for how long one full swing should take. You choose the length of the string, then run it to see how long one swing really takes.
The key idea
For a gentle swing, the time for one full swing depends only on the string length and the pull of gravity (T = 2π√(L/g)), not on how heavy the bob is. A longer string swings more slowly, and the same string swings faster where gravity is stronger.
Try this
Run it once, see whether one swing takes too long or too little time, then shorten the string to speed the swing up or lengthen it to slow it down.