An object dropped from rest from the top of a tall building on Planet X falls a distance d (t )equals 8 t squared feet in the first t seconds. Find the average rate of change of distance with respect to time as t changes from t 1equals2 to t 2equals5. This rate is known as the average velocity, or speed. The average velocity as t changes from 2 to 5 seconds is nothing StartFraction feet Over sec EndFraction .