The Skinny on Acceleration
Since acceleration is defined as the change in velocity per change in
time, we can say the following:If a is in the same direction as v, then the object is speeding up.If a is in the opposite direction as v, then the object is slowing down.If a = 0 in the direction of v, the object’s speed is not changing (though its
velocity may be, if there is acceleration perpendicular to the velocity).This means that, for example, positive acceleration does not necessarily
imply that an object is speeding up. If the velocity is negative, positive
acceleration means that the velocity is becoming less negative (slowing
down).We will discuss this further in Chapter 3.