Kinematics question - Physics!?

Question

A drag racer can accelerate from rest at the rate of 70km/hr/sec for 400m.

a) What is the car's velocity at the end of the track?

b) How long will it take to stop?

Please help me out with a step-by-step explanation. I already have the answers to these questions but I don't understand how to get to them! I would really appreciate a quick response. :)

Answer 1

Phony question since the acceleration decreases as speed increases. Anyway.. Open your book (! you can do it!) to the page with the equation Vf^2-Vi^2=2* acceleration * distance.

Note also that the velocity is unknown. Velocity is vector of direction and speed. You are calculating speed; the direction is unknown.