Categorize each feature as a physical system or a human system
agriculture
railroads
houses
weather events
volcanic eruptions
land formation
physical systems
human systems

answer:

human systems are: railroad, houses, agriculture

physical system are: weather events, volcanic eruptions, land formation

explanation:

1.human systems are things that people make, do, like with houses, they build homes.

2. physical systems are things that are formed by themselves, on mother earth, like weather is interchangeable we as humans can't control weather, for example if it's supposed to rain tomorrow i can't make it be summer and snow.

to act quickly in times of danger to the united states

because you have to act quickly if you want to live/survive.

declare war, appoint military officers, sign treaties, make alliances