Why do scientist use models to study atoms

Abird flies directly overhead from where you stand at an altitude of 300.0 m and at a speed horizontal to the ground of 20.0 m/s. the bird has a mass of 2.0 kg. the radius vector to the bird makes an angle \thetaθ with respect to the ground. the radius vector to the bird and its momentum vector lie in the xyxy-plane. what is the bird’s angular momentum about the point where you are standing?

Contains chemical energy. a. heat b. light c. natural gas

Which statement correctly describes the interaction between magnetic poles? north and south poles attract each other. north and south poles repel each other. two north poles will attract each other. two south poles will attract each other.