What is the velocity of the ball 0.8 seconds after it’s released ?

Need more details, what is the slope of the line, etc.

It depends.

In order to answer the question, a person has to know:

-- the velocity (speed and direction) of the ball WHEN it's released

-- whether the ball has any net electric charge

-- whether there's any other net electric charge in the neighborhood

-- the mass of the ball, if any net charges are involved

-- what planet is nearest to the ball

-- the acceleration of gravity on that planet

Each of these details has an influence on the answer.  That is, if one of them changes, then the answer changes.  Now, it hasn't escaped my notice that you neglected to provide ANY of this information, so there's no way to even begin to concoct an answer.

Right now, the question is a lot like me asking you "How much will I weigh 8 seconds after I finish eating the steak ?".