Question

When a particle moves with a constant velocity the accelaration will be +ve or -ve or zero?

Answer 1

zero.at constant velocity and accleration.

Answer 2

Acceleration = Change in velocity / time taken

Change in velocity = Final velocity - Initial velocity

If a particle moves with a constant velocity , the acceleration will be zero in most of the cases .Cases like uniform circular motion will have centripetal acceleration = v²÷r .

Your question is case dependent.