What is Thermal Energy?
Have you ever wondered
what makes something hot? The answer may be more simple than you think. The
temperature of an object increases when the molecules that make up that object
move faster.
Thermal energy is energy
possessed by an object or system due to the movement of particles within the
object or the system. Thermal energy is one of various types of energy, where 'energy'
can be defined as 'the ability to do work.' Work is the
movement of an object due to an applied force. A system is
simply a collection of objects within some boundary. Therefore, thermal energy
can be described as the ability of something to do work due to the movement of
its particles.
Because thermal energy
is due to the movement of particles, it is a type of kinetic energy,
which is the energy due to motion. Thermal energy results in something having
an internal temperature, and that temperature can be measured - for example, in
degrees Celsius or Fahrenheit on a thermometer. The faster the particles move
within an object or system, the higher the temperature that is recorded.
Application of Thermal Energy
Let's take a look at a
simple example of thermal energy. A heated element on a stove contains thermal
energy, and the more you turn up the stove, the more internal energy the stove
contains. At the very basic level, this thermal energy is the movement of the
molecules that make up the metal of the stove's element. I know you can't see
the molecules moving, but they are. The faster the molecules, the more internal
thermal energy they contain.
Now let's place a pot
of water on top of the heated element. What happens? The stove works, right?
Well, not as we would typically think of it. Here, 'work' is referring to 'the
movement of something when a force is applied.' Specifically, the thermal
energy of the stove causes the particles of the pot and eventually the water to
move faster. The internal energy of the heated element is transferred to the
pot and ultimately the water within the pot. This transfer of thermal energy
from the stove to the pot and to the water is referred to as heat.
It is very important to keep these terms straight. In this context, heat is
the term we use to refer to specifically the transfer of thermal energy from
one object or a system to another, transfer being the key. The thermal
energy is the energy possessed within the object or within the system due
to movement of particles. They're different - heat and thermal energy.
You can feel the heat
if you hold your hand above the stove. The heat, in turn, speeds up the
molecules within the pot and the water. If you place a thermometer in the
water, as the water heats up you can watch the temperature rise. Again, an
increase in internal energy will result in an increase in temperature.
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