thrown Definition and 2 Threads

The answer given is -10m/s2 because of constant downwards acceleration of gravity. i would like to know why is it not 0 at its peak height. at the top, velocity is momentarily 0, since acceleration is the change in velocity, change in 0 = 0. so why issn't a = 0? thanks

Was the approach used by the referenced tutor correct? In my understanding, the set up equation ought to be, ##s=-h, u=16## as the stone is being thrown upwards and ##g=-9.8## giving me, ##-h = 64 - \dfrac{1}{2}×9.8 ×16## ##-h=-14.4##m ##h=14.4##m , or it does not really matter.