d = 1/2 (a)(t)^2 = 160 m
at rest, Vo = u = 0 m/s
I found the final velocity by using
v = u +at = 0 + (20)(4) = 80 m/s
d = vt
t = 160 m / 80 m/s = 2 s
I might be wrong at this
I know d= Vot - 1/2 (a)(t)^2
By any chance, what textbook are you using?
A test rocket is fired up from rest. The net acceleration is 20m/s^2 upward and continues for 4.0 seconds, at which time the rocket engines cease firing. What maximum elevation does the rocket reach?
2 answers
h=at²/2=20•16/2=160 m