4. which model best describes the particles of a solid and their motion?
o bricks cemented together in a wall
o beads moving around in a rattle
o people seated in an auditorium
o students walking through a crowded hall

People seated in an auditorium

Explanation:

The arrangement of particles in a solid are fixed, vibrations still occur because they have internal energy, however they cannot move freely due to the intermolecular forces that hold them together.

Bricks cemented together in a wall: This model is not the most accurate, because yes the particles are in a fixed position, but the bricks do not show the vibrations of the molecules.

Beads moving around in a rattle: This model would rather represent gas molecules, because they move freely.

People seated in an auditorium: This is the most accurate, because even though they are seated in a "fixed" position, they can still "vibrate" (they can turn and talk to the people on either side of them. They are never completely still).

Students walking through a crowded hall: This model would rather represent liquid molecules, because they are not fixed in one position, but they are not running around either (like gas molecules).

grav forces affect all objects magnetic forces affect magnetic objects and electric currents