# Homepage

#### Physic: Energy topic

Energy is the ability to do mechanical work, give off heat or emit light. Energy is a state variable and, in closed systems, a conservation variable.
Energy is vital. People, animals and plants need them for their development. Technical devices such as radios, refrigerators, televisions or computers need energy to operate. Without energy, no train would travel and no airplane would fly. Even so, most of the time you cannot see, feel or touch energy. But you can recognize them by their effects -  https://domyhomework.club . In general, the following applies to the physical quantity energy in physics:

1 kJ  = 1,000 J
1 MJ  = 1,000 kJ = 1,000,000 J
1 GJ  = 1,000 MJ = 1,000,000 kJ = 1,000,000,000 J

Energy as a quantity of state and conservation

The physical quantity energy characterizes the state of a body, an electric field or a magnetic field. In physics -  physic helper  , such a quantity is called a state quantity in contrast to a process quantity that characterizes a process.

For a closed area or - as they say in physics - for a closed system, the total energy is always retained. The energy is thus also a conservation quantity for which a conservation law - the energy conservation law - applies.

Forms of energy and energy carriers

Energy can come in different forms, e.g. B. in the form of electrical, thermal, mechanical or chemical energy or as energy of electrical and magnetic fields. More detailed information can be found under the keyword forms of energy . Bodies or areas of space that have energy are called energy carriers or energy sources - https://domyhomework.club/engineering-homework/ . More detailed information on this is given under the heading "Energy carriers" .

Changing energy

• In a closed area (closed system) the total energy always remains the same, but:
• Energy can be transferred (transported) from one body to other bodies,
• Energy can be converted from one form to another,
• Energy can be devalued, ie converted into forms that are no longer usable for humans;
• Energy can be stored.