Question

choose the correct answer.
what happens when thermal energy increases?
particles slow down and the substance contracts.
particles speed up and the substance expands.
particles speed up and the substance contracts.

Explanation:

When thermal energy increases, the kinetic energy of particles increases. This causes the particles to move faster (speed up). As the particles move more vigorously, they tend to occupy more space, leading to the expansion of the substance.

Answer:

Particles speed up and the substance expands.