Acceleration Problem

1. Mar 18, 2014

poptaguser

1. The problem statement, all variables and given/known data
A runner wishes to complete a 1600m races in 5.0 min. She accelerates to racing velocity in the first 15s of the race then travels at a constant velocity for the next 4.0min. At this point she still has 250m to go. What must her acceleration be over the remaining distance in order for her to finish the race next time?

2. Relevant equations
The 5 BIG Kinematic Equations

3. The attempt at a solution
Δdτ = 1600m
ΔT = 300 seconds

2. Mar 18, 2014

guitarphysics

Ok, you're gonna have to make more of an attempt than that- you just listed the given information! Try to get some more relevant information, like: What remaining distance is left for the runner when she has to start accelerating? What's her velocity at that point? How much time does she have to cover that extra distance? If you consider these variables and how they fit into the kinematics equations, you should be able to figure it out.