Is final velocity a vector or scalar?

Question

A ball starts from rest at point A and rolls .9 meters east to point B with an average velocity of 2 m/s. What was the velocity of the ball at B?

Given:

Vi=0 m/s 

d (displacement)= .9m east

average velocity= 2 m/s 

Vf= ???

 

average velocity = Vf + Vi divided by 2

 

is the answer 4 m/s or 4 m/s East? 

Does the answer for final velocity include direction or no?

                            

 

 

Answer 1

v_i = 0  (started from rest)

 

<v> = average velocity = 2 m/s  (given)

 

<v> = (v_i + v_f)/2 ⇒ 

 

v_f = 2<v> - v_i = 2(2 m/s) - 0 = 4 m/s

 

Velocity is a vector, so the complete answer must have both a magnitude and direction.  Therefore

 

v_f = 4 m/s east

 

or

 

v_f = (4 m/s)i  (if you are familiar with the i, j, k notation).