Simple pendulum

AP Physics C: Mechanics EK 7.5.A.3 defines it as a special case of a physical pendulum in which the hanging object can be modeled as a point mass a distance $\ell$ from the pivot. The period is

$T_p = 2\pi\sqrt{\frac{\ell}{g}}$

which is printed on all four AP Physics equation sheets. With $g = 9.8 \text{ m/s}^2$, a 1.0 m pendulum has $T_p = 2.0$ s.

Two things it does not depend on. Mass, because $m$ cancels: the same gravitational force that restores the bob also resists its acceleration. And amplitude, by EK 7.3.A.2.

The small-angle condition is part of the formula, not a footnote. AP Physics 1 EK 7.2.A.1.ii gives $T_p$ for a pendulum displaced by a small angle, and EK 7.1.A.2.iii says a pendulum's motion can be modeled as simple harmonic motion because the restoring torque is proportional to the angular displacement, which only holds for small displacements. C: Mechanics writes the approximation out as $\sin\theta \approx \theta$ (EK 7.5.A.2.ii). Swing the bob through 60 degrees and the true period runs longer than the formula returns.

Note the $g$ in the formula: a pendulum clock keeps different time on the Moon, while a mass on a spring does not care.

Worked pendulum problems live in the SHM guide and the SHM practice set.