The displacement of a particle in simple harmonic motion is given by $x = 5\sin 4t$, where $x$ is in metres and $t$ in seconds. Find the amplitude and period of the motion.

Comparing with $x = A\sin\omega t$: $A = 5$ m and $\omega = 4$ rad s$^{-1}$. The period is $T = \dfrac{2\pi}{\omega} = \dfrac{2\pi}{4} = \dfrac{\pi}{2}$ s. Reading the 4 as the period confuses angular velocity with time.