Question

(1) when do you say that an object has positive acceleration?
(2) when do you say that an object has negitive acceleration?

Answer 1

when the final velocity on an object is greater than initial velocity positive acceleration takes place and when the final velocity of an object is smaller than the initial velocity negative acceleration takes place

Answer 2

Hello friend When the acceleration of body act in the direction of motion then this kind of acceleration is positive. In increase velocity or speed of body.  When the acceleration of body act in the opposite  direction of motion and it reduces its velocity or speed thrn this kind of acceleration is negative acceleration.  Hope it helps you.