Given:
u(initial velocity)=0
v(final velocity)=31.4ft/s=9.57m/s
time taken to cover the distance=1.2 s
Now we know that
v = u + at
Where v is the final velocity
u is the initial velocity
a is the acceleration
t is the time taken to cover the distance
Substituting the given values in the above formula we get
v= u + at
9.57=0+ ax1.2
a=26.17 m/s^2