Heat in everyday life
Heat in everyday life
Heat that comes to Earth from the Sun is essential for all life on the planet. Learning how to use heat made it possible for human civilisations to develop and exist. From a hot meal, to how we build our houses, to industrial design - we apply our knowledge about heat, temperature and thermal properties in practically every aspect of our lives. We do it without even thinking about it. Hard to believe?
Let’s look at some examples! If you ever struggled to open a jar, you might have noticed that it becomes easier to remove the lid if you run hot water over it. This is because the metal lid becomes bigger when it gets hotter - it expands. This happens to most materials and is called THERMAL EXPANSION. The knowledge about thermal expansion can be used to build bridges or railroad tracks.
Bridges and tracks are made of smaller parts which expand and become longer when it’s hot. This might deform the tracks or bridge and lead to breakdowns and serious accidents. That’s why we join the parts in a special way, which allows them to expand and contract freely. Another example of thermal expansion of materials is devices we use to measure temperature - thermometers. They use the expansion of metals or liquids like mercury, to indicate how hot or cold something is.
Since we can measure temperature, we can also observe that heat moves from warmer objects to colder ones, and it can happen in different ways. It can be transferred through direct contact like from a hot plate on a stove to your delicious soup in the pot. It can travel between distant objects through air or space in the form of radiation - for example the heat from the Sun reaching the Earth. The heat can also travel with the flow of particles inside liquids or gases. You can experience it when the air heated up by a radiator spreads across your room.
But some materials make it difficult for heat to travel through - we call them INSULATORS. An example of an insulator would be a woolen sweater you wear in the winter. It keeps you warm because it doesn’t let the heat produced by your body escape. We also use insulating materials to keep the heat inside our houses. The most modern houses are built in such a way that barely any heat can escape.
Thanks to that, the heat of electrical appliances and people living inside is enough to keep the houses warm. Such houses often do not need any extra source to heat the space like a fireplace or a radiator! This makes them very environmentally -friendly and energy-efficient. We call them PASSIVE HOUSES. While passive houses keep all the warmth inside, a fridge does exactly the opposite.
It takes away all the heat from the inside and moves it to the outside. Thanks to that the inside of the fridge remains cold even on the hottest day. A fridge is an example of a heat pump. Heat pumps can also be used to pump hot air into or out of our houses, or to heat up water we use in our homes. Thermal expansion, measuring temperature, heat transfer, insulators and heat pumps are only some examples of how we use heat in everyday life.
Can you think of any other examples?