Average Acceleration

 Acceleration = a change in speed: (Speeding up…Slowing down… or changing 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. 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 2 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 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 - 20 = 260 = 52 mph/min Time          t2 – t1 5- 0 5

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