A 05-Kg Model Helicopter Initially at Rest on the Ground,starts to to Move

Multiple Choice

A 0.5-kg model helicopter initially at rest on the ground,starts to move directly up under the effect of a lift force of magnitude of 7.4 N.After 12 seconds the engine stops and the helicopter starts free fall.Ignoring air resistance,calculate the helicopter's velocity just as the engine stops.

A) 59.9 m/s
B) 178 m/s
C) 48.4 m/s
D) 38.0 m/s
E) 118 m/s