Final answer:
An object can accelerate by speeding up, slowing down, or changing direction. To calculate average acceleration, one must determine the change in velocity and time. Acceleration is the rate of change of velocity over time based on Essential Knowledge 4.A.2.
Step-by-step explanation:
An object can accelerate in three main ways: by speeding up, slowing down, or changing direction. When calculating average acceleration, we need to determine the change in velocity and the change in time, then use these values to calculate it.
Acceleration is defined as the rate of change of velocity with time, as expressed by Essential Knowledge 4.A.2. For example, if an athlete accelerates uniformly from an initial velocity of 0 m/s to a final velocity of 4 m/s in 2 seconds, the acceleration is calculated as (final velocity - initial velocity) / time, which would be (4 m/s - 0 m/s) / 2 s = 2 m/s².