The blank of an object describes the speed and the direction in which it is going

This is known as Velocity.
Velocity is the speed and direction of an object. The formula for velocity is:
V = D/T, meaning Velocity = Distance divided by Time.
I hope this helps!

Betray, destroy, and obey do not need to be changed to add the suffix -ed, because the "y" at the end of each word is preceded by a vowel  (so  they would be spelled  "betrayed," "destroyed," and "obeyed").

but hurry is different; it has to  be spelled "hurried" because the "y" at the end of "hurry" is preceded by a consonant.