Question

what happens to the particles when heat is added to a substance? the particles slow down. the particles speed up. the particles disappear.

Explanation:

When heat is added to a substance, the thermal energy is transferred to the particles. According to the kinetic - molecular theory, the kinetic energy of particles is related to temperature. As heat (a form of energy) is absorbed, the temperature of the substance increases. The kinetic energy of particles \(K = \frac{3}{2}kT\) (where \(k\) is the Boltzmann constant and \(T\) is the temperature in Kelvin). As \(T\) increases, the average speed of particles \(v=\sqrt{\frac{3kT}{m}}\) (where \(m\) is the mass of the particle) also increases. So the particles speed up.

Answer:

The particles speed up.