Acceleration of a runner to finish in his desired time

[Pioneer98]

Homework Statement

A runner hopes to complete the 10,000 meter run in less than 30 minutes, after exactly 25 minutes there are 1900 meters to go. The runner must then accelerate at 0.22 m/s^2 for how many seconds in order to achieve the desired time?

Homework Equations

V=change in distance/change intime
avg acceleration=change in velocity/time elapsed

The Attempt at a Solution

V before 25 minutes=5.4 m/s
V after 25 minutes=6.33 m/s
Avg. Acceleration=.24 seconds (know that's not right)

 

[azizlwl]

V before 25 minutes=5.4 m/s=Correct
Question is what is time taken
Acceleration given.

Now we call it u not V
You have intial velocity 5.4 m/s, distance to cover and use SUVAT to find time needed.

 

[NascentOxygen]

The runner accelerates steadily at 0.22m/s over a time t seconds. Then he runs at that new speed for 300-t seconds.