Insights into Physics – Energy

Energy is the ability to do some work or change some state. It can move something or heat or cool something. The result of energy activity is work, the transformation of energy into something else. In other words, energy exists in different forms and is transformed into different kinds of physical change. Energy is not created or destroyed in any form; it only changes its form. This is the law of conservation of energy, a fundamental principle of macrophysics. Many technologies are based on it.

Přeměna energie

Internal energy and heat

Every object in the universe is made up of particles in constant disorderly motion.Therefore, every molecular system has a certain amount of internal energy.This is related to the internal particle structure and is produced by the motion and vibration of atoms and molecules. The random motion of molecules produces kinetic energy, while the forces they exert on each other (interactions) are called potential energy. The sum of the kinetic energy and total potential energy of these particles is called the internal energy. The faster the particles move, the greater the internal energy of the object. Heat is generated and the object begins to heat up. Internal energy can be changed, for example, by rubbing, heating, or cooling an object. The unit of internal energy is the joule.
Zvuková energie

Sound energy

Sound energy is a type of pressure wave. When the human ear picks up these longitudinal waves, they are converted into electrical impulses and transmitted to the brain, which evaluates them as sound. The loudness of the sound depends on the magnitude of the pressure change, and the pitch of the sound depends on how fast the waves follow each other, i.e., the frequency of the waves. Lower frequency sounds are called infrasound and higher frequency sounds are called ultrasonic. The speed of sound depends on the environment in which it is transmitted and its density. At zero altitude, sound travels at about 340 m/sec (1,224 km/h), but at higher altitudes it travels more slowly. Underwater, however, it travels five times faster.

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