Question

you are standing up in a subway train. the train suddenly stops but your body continues to move forward.

Explanation:

Newton's First Law of Motion (Law 1) states that an object in motion stays in motion unless acted upon by an external force. When the subway train stops (external force on the train), the person's body (due to inertia) continues moving forward as there's no immediate external force to stop it. Law 2 is about force, mass, and acceleration ($F = ma$), and Law 3 is about action - reaction pairs. This scenario is about inertia (Law 1).

Answer:

Law 1