Describe a model that could represent the total energy of a system as a relationship of the motion of particles on both microscopic and macroscopic level

Which explanation describes the forces involved for a person to walk down the sidewalk? a. the person's feet push backward on the sidewalk; the sidewalk pushes backward on the person. b. the person's feet push forward on the sidewalk; the sidewalk does not push on the person. c. the person's feet push backward on the sidewalk; the sidewalk pushes forward on the person. d. the person's feet push forward on the sidewalk; the sidewalk pushes forward on the person.

Describe the function of the endomembrane system? what organelles are involved?

Where do magnetic lines of force enter earth?