College Physics (7th Edition)

For sine function, the initial position is Zero as $sin 0 =0$. The initial velocity is maximum as $cos 0 =1$. The acceleration is zero because it is proportional to $sin\omega t$, which is zero. For cos function, things are reversed. The initial position and acceleration are at their maximum, but initial velocity is zero.
For sine function, the initial position is Zero as $sin 0 =0$. The initial velocity is maximum as $cos 0 =1$. The acceleration is zero because it is proportional to $sin\omega t$, which is zero. For cos function, things are reversed. The initial position and acceleration are at their maximum, but initial velocity is zero.