An object is moving initially with a velocity of 4.7 m/s . after 3.9 s the object's velocity is -2.1 m/s . what is the object's average acceleration during this time?
i believe that the vf is -2.1 m/s vi should be 4.7 m/s and the t should be 3.9s but its #confused

The acceleration of the object is 0.67m/s^2 west.

Explanation: Here we are given the initial velocity and final velocity as well as the time taken. Acceleration is the change in velocity per unit time, thus the equation becomes.

a=dv/t

a=vf-vi/t

a=-2.1-4.7/3.9

a= 0.66m/s^2 west

it is called kinetic energy