A distressed car is rolling backward, downhill at 3.0 m/s when its driver finally manages to get the engine started. What velocity will the car have 6.0 s later if it can accelerate at
3.0 m/s??

Explanation:

Acceleration is equal to the change in velocity over the change in time, or

where the change in velocity is final velocity minus initial velocity. Filling in:

Note that I made the backward velocity negative so the forward velocity in our answer will be positive.

Simplifying that gives us:

and then isolating the final velocity, our unknown:

3.0(6.0) = v + 3.0 and

3.0(6.0) - 3.0 = v and

18 - 3.0 = v so

15 m/s = v and because this answer is positive, that means that the car is no longer rolling backwards (which was negative) but is now moving forward.

the amount of current in the coil