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.
Acceleration is a change in velocity. The change can be in direction only (such as centripetal acceleration during uniform circular motion). Under these circumstances, velocity is changing but speed is not. So constant speed does not imply zero acceleration.