Tech A says that some electric actuators are positioned by an A/C ECU which checks the air flow with sensors. Tech B says that electric actuators are positioned by an A/C ECU and some actuators have a potentiometer to tell the A/C ECU the position of the door. Who is correct?

With i really need the correct answer!

Ahot-air balloonist, rising vertically with a constant speed of 5.00 m/s releases a sandbag at the instant the balloon is 40.0 m above the ground. after it is released, the sandbag encounters no appreciable air drag. compute the velocity of the sandbag at 0.250 s after its release.

Work out sian speed for the first 30 minutes of her journey. give your answer in km/h.