There is no such thing as Deceleration!
Well, not technically
Objects do not simply "decelerate," and stop, their energy is actively taken from them, and are stopped.
This is known as Negative acceleration
Negative acceleration is the force applied
by all things against
an object that take energy from its motion, such as friction, or a large unmoveable
object, and either re-apply it (such as the large object), or convert it to heat (friction). As such, all objects opposing
this movement apply a negative
acceleration to the object.
Say I'm going forward at 10 m/s, to stop me a force must be applied. To stop me in one second, you apply a negative acceleration of -10m/s and I'll come to an instant
halt. Unless that force is applied
(or any other force of some varying magnitude), I'll just continue on, never stopping