Sprint Acceleration and Time to Top Speed Calculation

[sprinter08]

Homework Statement

A world-class sprinter can burst out of the blocks to essentially top speed (of about 11.5m/s) in the first 15.0m of the race.
a.) What is the average acceleration of this sprinter?
b.) How long does it take her to reach that speed?

Homework Equations

The Attempt at a Solution

I hope that I have solved the problem correctly. I drew a picture and followed a 12 step process assigned by my teacher. I just want to know if my answers are correct to know if what I am doing on the rest of my homework is correct.
a.) a= 4.408 m/s^2
b.) t= 2.608 s

 

[silvashadow]

a. Well, vf^2=vo^2+2ad, vo=0
a ends up to be 4.40833333m/s^2
b.vf=v0+at, vo=0
t ends up to be 2.60869565s
so both answers are correct

 

[||spoon||]

2.609...(according to silvershadow)

Sorry to be pedantic ;p