Math/Physics Question?

Question

A train traveling at a speed

of 321 km/h requires 1.35 km to come to an

emergency stop.

Find the braking acceleration for this train,

assuming constant acceleration. Answer in m/s^2

Answer 1

vf=321

vi=0;

d=1.35

vf^2=vi^2+2ad

103041=2(1.35) a = 2.7a

a=-38163.33m/s^2