Fill the Bucket
The server picks a water tank, the width of its hole and a bucket on the floor, plus a moment in time (always achievable), you set the height of the hole, and a real draining-tank model judges whether the jet is landing in the bucket at that moment. Landing it in the bucket refunds your run.
About this simulation
What it shows
A puzzle on a draining water tank: its size, the width of the hole and a bucket on the floor are given, along with a moment in time. You choose the height of the hole, then run it to see where the jet is landing at that moment.
The key idea
The jet leaves the hole sideways at a speed set by the water depth above it, then falls to the floor. A higher hole means a longer fall but less water above it, and as the tank drains the jet slows, so where it lands depends on the hole height and the moment you look.
Try this
Run it once, see whether the jet falls short of the bucket or overshoots it, then raise the hole to send the jet further or lower it to shorten the jet.