State what simple harmonic motion means.
Fig. 3.2 shows the variation of the velocity $v$ of sphere P with the displacement $x$ from its mean position. Use Fig. 3.2 to determine the frequency $f$ of the oscillations of sphere P.
The period $T$ of the oscillations of sphere P is given by $T = 2\pi\sqrt{\frac{L}{g}}$, where $g$ is the acceleration of free fall. Use your answer in (b) to find the length $L$.
A second pendulum has a sphere Q suspended from a thread. Spheres P and Q are identical. The thread supporting sphere Q is longer than the thread attached to sphere P. Sphere Q is displaced and then released. The oscillations of sphere Q have the same amplitude as the oscillations of sphere P. On Fig. 3.2, sketch the variation of the velocity $v$ with displacement $x$ for sphere Q.