3 Ways to Accelerate   Speed up…Slow down…or Change direction Average acceleration is the rate at which velocity changes.   Average acceleration is the change in velocity divided by an elapsed time. For instance, if the velocity of a marble increases from 0 to 60 cm/s in 3 seconds, its average acceleration would be 20 cm/s/s (or 20 meters per second, for every second it travels) . This means that the marble’s velocity will increase by 20 cm/s every second. See the table below:

 Time (Seconds) Velocity (cm/s) 0 0 1 20 2 40 3 60 4 80

 Here is the formula we will use:

 Average Acceleration = Velocity Time = “change in” or “difference of”

 Here is another way of looking at the formula:

 Average Acceleration = Velocity = v2 – v1 Time         t2 – t1

Where V2 is the Final Velocity and V1 is the Starting Velocity and

t2 is the Final Time and t1 is the Starting Time Sample problem) At 12:00, a rocket begins to accelerate from 20 mph. At 12:05 the rocket is traveling at 280 mph. What is the acceleration of the rocket?

 Average Velocity = Distance = d2 – d1 = 280 mph – 20 mph = 260 mph = 52 mph/min Time          t2 – t1 5 min – 0 min 5 min