Changing Velocities: Acceleration or Deceleration?

[Prototype44]

Homework Statement

I need to know if these set of velocities changing correspond to acceleration or
deceleration?

-0.9m/s - +4m/s
+4m/s-4.5m/s

Homework Equations

The Attempt at a Solution

I think that

+4m/s-+5m/s is considered acceleration in the same direction
-5m/s-7m/s is considered acceleration in the negative direction

My chemistry told me that it the first example would be an example of a deceleration then an acceleration due to it becoming zero and then accelerating to +4m/sec and that the same idea applies to the second example.

 

[Saxby]

m/s (which is Metres per second) is the unit for Velocity not acceleration.

I don't know about everybody else, but personally I am not sure what your asking

 

[Prototype44]

lets say those were in m/sec^2, would they be deceleration, acceleration or a combination of both?