help me dont know which equation or how to do?

Question

toy rocket is launched vertically from ground level (Y=0), at time, t=0.0s. The rocket engine provides constant upward accleration during the burn phase. At the instant of engine burnout, the rocket has risen to 64 m and aquired a velocity of 60m/s. The rocket continues to rise in unpowered flight, reaches max height, and falls back to the ground. The time interval, during which the rocket engine provides upward acceleration, is closest to?

Answer 1

Some assumptions:
Assume air resistance is negligible
Assume the mass loss of burned fuel is negligible

Since constant acceleration is stated
v=a*t
and
d=.5*a*t^2

You know v=60
so a*t=60
you know d=64
so
64=.5*60*t
t=64/30

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