
Mark I. answered 03/31/19
EMT Turned Teacher
I am not sure why nobody answered your question and it probably won't help now. Buuuut, I went ahead and solved it:
Use two kinematic equations: vf = v0 + at & vf2 = v0 + 2aΔx
1st find the final velocity using the second eqn. And, then plug that into the first equation and solve for time.
a = 4.5m/s2
initial velocity= 15m/s
Δx = 45m
vf2 = v0 + 2aΔx = 152 +2(4.5)(45) = 630=
vf = √630 ≅25.1 m/s
Manipulating our 1st equation we get: (vf - v0)/a = t
t = (25.1 - 15)/4.5 = 2.24 s