Remark
The usual question is either what is the deceleration or how far did she go before she stopped.
Equation
For Distance
d = (vf + vi)*t / 2
For Deceleration
a = (vf - vi)/t
Solution (Distance)
d = (vf + vi) * t/2
d = (15 + 0) * 2.5 / 2
d = 15 * 2.5 /2
d = 37.5/2
d = 18.75
Solution Deceleration
a = (vf - vi)/t
a = (-15)/2
a = - 7.5 m/s^2 It is minus because you are slowing down, not speeding up.
