A toy rocket is launched vertically from ground level (y = 0 m), at time t = 0.0 s. The rocket engine provides constant upward acceleration during the burn phase. At the instant of engine burnout, the rocket has risen to 90m and acquired a velocity of 67 m/s. The rocket continues to rise in unpowered flight, reaches maximum height, and falls back to the ground. The upward acceleration of the rocket during the burn phase is closest to: O 0.04 m/s2 O 50 m/s2 O 25 m/s2 O 0.8 m/s2 O 0.4 m/s2