ancillae. 1  nominative plural of. 2  genitive singular of. 3  dative singular of.  vocative plural of.
Acceleration is the time rate of change of velocity. If velocity is constant, then. acceleration is zero. Note: 100 km per h for 10 seconds is a constant speed, but not necessarily a constant. velocity, since we're told nothing about the direction.
When you brake to stop your car, you are decelerating. When a ball rolls on the ground and slows down to a stop, the ball is decelerating. Deceleration is the term used for acceleration that causes an object to slow down, while acceleration is motion where the speed of an object changes every second. However, in everyday usage, acceleration is usually taken to mean speeding up. Now that you know what deceleration is, let's look at an example.