Final answer:
The car should be in Park (P) when starting an automatic transmission. Starting the engine in Neutral (N) may cause the car to rock due to the torque produced by the engine. The angular momentum of the car is not conserved for long in this situation.
Step-by-step explanation:
When starting an automatic transmission, the car should be in Park (P).
this is because the Park position securely locks the transmission, preventing the car from moving while the engine is running.
When you start the engine with the transmission in Neutral (N), the car may rock in the opposite sense of the engine's rotation due to the torque produced by the engine.
This rocking motion occurs because the transmission is not locked in place.
Conservation of angular momentum doesn't play a major role in this situation as the car is not rotating or in motion for an extended period.
Therefore, the angular momentum of the car is not conserved for long.