Final answer:
The CRJ 550/700 engine relight windmilling refers to restarting the aircraft's engines during descent by using airflow to spin the turbines.
Step-by-step explanation:
Understanding CRJ 550/700 Engine Relight Windmilling 25,000 ft to Sea Level
The CRJ 550/700 engine relight procedure from an altitude of 25,000 feet to sea level is a specific aspect of aeronautical engineering that relates to the ability of an aircraft's engines to restart, or relight, during flight after being extinguished. The process of windmilling refers to the rotation of the airplane's engine turbines due to the airflow as the aircraft descends, which can be used to help restart the engines without the use of starters. This is a critical procedure for safety in the event of an engine shutdown at high altitudes.
Part (a) sets up a scenario trying to calculate the time it would take for a 1.50×105-kg airplane with engines that produce 100 MW of power to reach a speed of 250 m/s and an altitude of 12.0 km if there was no air resistance to impede its motion. Part (b) goes on to calculate the actual power used by the airplane if it takes 900 seconds to perform this task. Part (c) then asks to calculate the average force of air resistance if the airplane takes 1200 seconds to reach the same objectives, with a hint to find the distance the plane travels in 1200 seconds assuming constant acceleration.