What remain constant in simple harmonic motion?

When a sound wave of frequency $300\mathrm{Hz}$ passes through a medium, the maximum displacement of the medium is $0.1 \mathrm{cm}$. The maximum velocity of the particle is equal to.

The time period of an oscillating body executing SHM is $0.05 \mathrm{s}$ and its amplitude is $4 \mathrm{cm}$. The maximum velocity of particle is:

Two simple Harmonic Motions of angular frequency $100 \mathrm{and} 1000 \mathrm{rad}/\mathrm{s}$ have the same displacement amplitude. The ratio of their maximum accelerations is$:$

A particle moves with simple harmonic motion in a straight line. In first $\tau \sec$, after starting form rest it travels a distance $a$, and in next $\mathrm{\tau } \mathrm{se}c$, it travels $2 \mathrm{a}$, in same direction, then$:$