Its acceleration is positive (in the same direction as the motion).

Why it’s positive

  • Acceleration is the rate of change of velocity with time: a=ΔvΔta=\frac{\Delta v}{\Delta t}a=ΔtΔv​.
  • If the velocity is increasing along a straight line, then Δv>0\Delta v>0Δv>0, so the acceleration is positive.
  • Positive acceleration means the object is speeding up in the direction it is already moving.

A simple example: if a car’s velocity changes from 5 m/s to 10 m/s in 2 s while going straight, its acceleration is 10−52=2.5textm/s2\frac{10-5}{2}=2.5\\text{m/s}^2210−5​=2.5textm/s2, which is positive.