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Physics

Pendulum Lab

Adjustable gravityLength controlPhysics sim
Lv 1♥♥♥Score 0Best 0

Tap the screen (or Space) to cut the rope. Swing the bob into the cup.

Compare copied swings without changing your challenge or lab.

Twin Period Bench

Predict which pendulum swings faster. Both copied setups run through the same physics engine. No challenge points or lab changes.

A · captured setup

B · experiment setup

Choose B's setup, make a prediction, then measure both.

Measured period is the time between two crossings in the same direction. Theory assumes a small swing; wide swings and damping can differ. “Same pace” allows a 0.5% difference. Double mass is capped at 5 kg.
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How to play Pendulum Lab

A ball hangs from a rope and swings back and forth. When you cut the rope, the ball flies off along the path it was moving on at that moment. Cut at the right moment and it drops into the cup.

  1. Watch the swing. The dotted line shows where the ball would go if you cut right now.
  2. Tap the screen, press Space, or press Cut rope when the dotted line points at the cup.
  3. You get 3 lives. A miss costs one. The levels keep going, and later ones add walls to bank shots off, a moving cup, and different planets.

Planets, scoring and the Lab

The game uses real gravity for Earth (9.81), the Moon (1.62), Mars (3.71) and Jupiter (24.79). On the Moon the ball floats and the swing is slow. On Jupiter everything is fast. Each cup is worth 100 points plus up to 100 for accuracy. Landing close to the middle is a bullseye for 50 more, and a bank shot off a wall adds 75. A streak of cups multiplies the total by up to 4. Your best score is saved in this browser.

Switch to the Lab tab to experiment with no lives and no score. Drag the ball to choose the start angle, then change the rope length, gravity, mass and damping with the sliders. You will see that mass does not change the swing time. The period depends on the length and gravity, T = 2 pi times the square root of L over g, for small swings. The Twin Period Bench compares two setups side by side.