Final answer:
A hung start in a turbine engine is a condition where the engine fails to reach idle speed during start-up. For the question on angular momentum, if a part of the turbine seizes, the pieces fly outward to conserve angular momentum without transferring it to the wing.
Step-by-step explanation:
A hung start in a turbine engine refers to a condition during the start-up process where the engine fails to reach the required idle speed. This results in the engine being stuck at lower speeds, unable to accelerate to an operational state. When this occurs, the turbine is not producing sufficient power, potentially leading to overheating and damage if not addressed promptly.
Concerning the question on angular momentum in jet turbines, because a turbine engine is designed to rotate at very high speeds, it has significant angular momentum. In the case that a part of the turbine seizes, the principle of conservation of angular momentum means that if a rotating system is experiencing no net external torque, its angular momentum remains constant. So, when a component in the turbine engine fails and causes the turbine to seize, the pieces that break off fly outward radially. They retain their speed and direction per the conservation law. This mechanism ensures that the angular momentum is conserved without transferring a significant amount of that momentum to the plane's wing, which could cause catastrophic structural damage.
To clarify, 'flying apart' means that the failed components of the jet turbine disperse in different directions. Each separated piece carries a portion of the engine's original angular momentum as it moves away from the center of rotation. The design of the turbine is such that these parts disperse within the engine casing and do not transfer the full force to the wing or other parts of the aircraft.