In order to understand the possible cause of a 'right side stomach pain', it may be helpful to know the organs and structures that exist in this region of the body. Diseases, infections, or irritation of any of these organs will lead to a right side abdominal pain.
At that one instant, its velocity is zero, even though its acceleration is still 9.8 m/secÂ². But velocity cannot REMAIN at zero for any length of time if the acceleration is nonzero.
At the peak of the trajectory, a vertically thrown object has gravity acting on it (accelerating it downwards at 9.8 m/s/s) while its velocity is zero. A simple example using calculus also suffices. which has zero velocity at [math]t=t_0[/math] and non-zero acceleration at [math]t=t_0[/math].