When you drill into a rock the heat is transferred by the metal bit into the rock as well. The potential energy stored in a drill when electricity flows through it is simply transferred. In physics, energy is a property of objects which can be transferred to other objects or converted into different forms, but cannot be created or destroyed.
As I mentioned at the outset all of the many forms of energy are convertible to other kinds of energy. The bottom line is that it obeys the conservation of energy. Common energy forms include the kinetic energy of a moving object, the radiant energy carried by light, the potential energy stored by an object’s position in a force field,(gravitational, electric or magnetic) elastic energy stored by stretching solid objects, chemical energy released when a fuel burns, and the thermal energy due to an object’s temperature.
What is heat? It is the energy stored in the vibrations of atoms,
In the 1930s, physicists started modeling atomic vibrations as particles. This is similar to the concept of light as both a wave and a particle we call a photon. Physicists called the sound wave particles “phonons,” derived from the Greek word for sound.
Today, physicists treat phonons as quasi-particles, having both wave and particle properties. Phonons carry both sound and heat. In the example of electric drill heat is carried primarily by the movement of electrons in the atoms.
Now heat and sound are related.
Sound is carried by periodic vibrations of atoms in gases, liquids and solids. When we talk to each other, the vocal chords of the speaker vibrate, causing the air coming from his lungs to vibrate as well. This creates sound waves, which then propagate through the air until they hit a listener’s eardrums and make them vibrate as well. From these vibrations, the listener can then reconstruct the speaker’s words.
Sound is affected by the surroundings in which it travels and by the frequency of the sound waves. We design musical instruments to manipulate the sound waves they produce. Further, we know that there are sound waves that are outside the range of human hearing, such as those produced by a dog whistle. As physicists have researched sound both inside and outside the range of human hearing, interesting properties have been discovered.
More than a hundred years ago, physicists understood that heat is simply the energy stored in the vibrations of atoms, and therefore realized that heat and sound are related.
(ack: Wikipedia/energy, the conversation-Joseph Heremans of 24 March,2015