Here's why:
* Heat is a form of energy: Heat energy is the energy associated with the random motion of atoms and molecules within a substance.
* Increased energy, increased motion: When you add heat, you are essentially adding energy to these particles. This extra energy causes them to move faster, vibrate more vigorously, and collide more frequently.
* Temperature is a measure of this motion: Temperature is a measure of the average kinetic energy of the particles in a substance. As the particles move faster, the temperature of the substance increases.
Think of it like this: Imagine a group of people sitting still. If you start giving them energy (like by playing music), they'll start moving around more. The more energy they have, the faster they'll move. The same principle applies to the particles within a substance.