When divided by △t, (vf - vi) is used to determine which characteristic? a. speed b. direction c. displacement d. acceleration

D.Acceleration

Explanation:

The acceleration of an object is defined as:

where

vf is the final velocity of the object

vi is the initial velocity of the object

is the time taken for the change in velocity to occur

Therefore, from the formula, we see that if we divide (vf - vi)  by △t, we get the acceleration.

this is poiselle's equation from fluid mechanic in physics. mech eng

that would be because of both gravity and friction. so     c