Change gravity or the string length and see how the swing period responds. Push the bob by dragging the sliders — the equation of motion runs live.
For small angles, a pendulum's period is T = 2π√(L/g).
Notice: doubling length only multiplies the period by √2, not 2. Change gravity to see how a pendulum on the Moon (g ≈ 1.62) swings much slower than on Earth.