Heat is a form of energy that can transfer from a higher temperature object to a lower temperature object when the two are brought together or in contact. At that time, two objects with different temperatures will appear heat flowing or moving.
Then, what heat changes can occur? And like what heat transfer? Check out the following review, which was launched from Gramedia.com!
Heat Change
Heat changes two substances that come into contact or come into contact. A number of heat change can occur in substances when they are brought together or put together, namely as follows.
1. Heat Can Change the Temperature of a Substance
Basically, every object has a temperature lower than absolute zero so the substance must have heat. This content makes it a determinant of how much heat an object’s temperature has.
Substances that are heated will receive additional heat so that its temperature increases or increases. On the other hand, a cooled substance releases heat so its temperature drops.
2. Heat Can Change Substances
Some types of substances that are given heat in a certain unit will change. For example, ice that is heated or heated will change from solid to liquid.
Then, if the heating process continues, the water will turn into a gaseous state. It occurs when a substance changes shape from the point of liquid to the melting point of an object.
Types of Heat Transfer
Heat Transfer (Ruswanti)
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Furthermore, heat is transferred to the contact of the objects that touch or regulate. There are several types heat transfer What can happen is as follows.
1. Conduction
By conduction, heat is transferred by passing through an intermediate substance such as a metal without being accompanied by a permanent movement of particles in the substance. For example, when heating a metal tip, the other metal end is also hot because of the conduction of heat from a high temperature to a low temperature.
The heated metal tip causes the metal particles to vibrate the other particles they are connected to. It stimulates heat transfer.
Other examples, the lid of the pot which is hot when used for cooking, the exhaust of the motorcycle becomes hot after the engine is started, and butter that melts when heated.
From the information above, it can be obtained the equation for heat transfer by conduction.
Laju Kalor = Q / t = kA (T2 – T1) / x
2. Conduction
Also Read: Definition of Energy and a Brief Explanation of Types of Energy
Convection is heat transfer which passes through a substance accompanied by the movement of parts of the substance. This transfer can occur in liquids or gases. Therefore, convection divided into two, namely as follows.
Displacement convection This is caused by the buoyant force without external factors, which is influenced by different types of objects. For example, in heating water.
The mass of hot water particles will rise away from the fire. Then, it is replaced with other water particles with a lower temperature. This process allows all the particles of the substance to heat thoroughly.
This displacement occurs in a forced or deliberate manner due to the influence of external factors, such as pressure. The heat is forced to move to the destination with the help of external factors.
For example, a fan that brings cold air to a hot place and a car radiator that has an engine cooling system.
Example of transfer by convection, among others, the up and down movement of green bean seeds when boiled, the up and down movement of water when heated, the occurrence of land and sea breezes, and the movement of hot air balloons.
From the information above, it can be obtained the equation for heat transfer in a way convection.
Heat Rate = Q/t = hA (T2 – T1)
3. Radiation
Radiation is heat transfer which does not use any intermediates. Therefore, this displacement does not always require the two objects to meet or touch each other. Heat will be radiated in all directions by the heat source, then flows in all directions it can go.
Every object can emit and absorb heat radiation, but the amount depends on the temperature of the object and the color of the substance. The more surface area a hot object has, the hotter the heat radiated to its surroundings.
For example, the warmth of a bonfire that can be at a certain distance, the palm of the hand feels hot when exposed to a light bulb that is burning, the heat from the sun’s rays to the earth and other planets.
From the information above, it can be obtained the equation for heat transfer by radiation.
Heat Rate = Q/t = σeAT4
Well, that was a review about the changes and heat transfer. Hope it is useful!
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