An acceleration/distance/velocity question.

[username111]

Homework Statement

As a traffic light turns green, a waiting car starts with a constant acceleration of 6.0 m/s^2. At the instant the car begins to accelerate, a truck with a constant velocity of 21 m/s passes in the next lane.

A)How far will the car travel before it overtakes the truck?

B)How fast will the car be traveling when it overtakes the truck?

Homework Equations

i have all of the following formulas:
vf = vi+at
d = (vf+vi)/2 x t
d = (vi)(t) + 1/2(a)(t)^2
vf^2 = vi^2 + 2(a)(d)

The Attempt at a Solution

i'm thinking i have to set a distance equation equal to the other one for A. I'm just not sure how to start the problem or anything. and for B, do i use what i'll get for distance and plug it into another equation?

 

[Redbelly98]

(a) Write two separate distance equations, one for the car and one for the truck. What can you say about these two distances when the car reaches the truck?