Which two statements are true about a system?

a system is a group of objects analyzed as one unit.

energy that moves across system boundaries is conserved.

there’s only one way to define the boundaries of a system.

all systems are made by humans.

Ineed the answer to question 1 , i’m desperate

(**i would really appreciate if this was answered soon** ) which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?

Which of the following characteristics of earth's relationship to the sun explains the existence of earth's seasons? choose all that apply. earth has a satellite called the moon, which rotates around earth. earth spins on its axis, completing one rotation each day. earth's axis always points in the same direction relative to the stars. earth's axis is tilted relative to its orbital plane. earth orbits around the sun, completing one orbit each year.