What is Simple pendulum? — Physics

Definition 28.3 High School Physics · Chapter 28 — Mechanical Oscillators and the Measurement of Time

A simple pendulum: a small bob of mass $m$ on an inextensible wire of length $L$ and negligible mass, swinging in a vertical plane. Of the two forces on the bob (Chapter 25), the tension is perpendicular to the motion, while the weight’s component along the trajectory points back toward the lowest point: the weight is the restoring force, opposing the displacement.

Forces on the bob: the tension T is perpendicular to the motion; the tangential part P_t of the weight always points back toward the vertical — the restoring force. — Forces on the bob: the tension $\vect T$ is perpendicular to the motion; the tangential part $\vect{P_t}$ of the weight always points back toward the vertical — the restoring force.

Examples

Example 28.6 (The seconds pendulum)

Which length beats the second, $T_0 = 2.00\,\mathrm{s}$ , one tick each way? Solving, $L = g\,T_0^2/4\pi^2 = 9.81 \times 2.00^2/4\pi^2 \approx 0.994\,\mathrm{m}$ . Nearly a meter: pendulum clocks are tall because seconds are long.

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Examples

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