Types of Expansion of an Object
Most substances will experience an enlargement if heated or reduced when cooled. When a substance is heated, the molecules contained in the substance will vibrate faster and the amplitude of the vibration will increase in size, as a result the distance between the molecules of the object will become larger and an expansion occurs. . Expansion can occur in solids, liquids, and gases. The magnitude of the expansion of a substance is very dependent on the initial size of the object, the rise in temperature, and the type of substance. The effect of the expansion of substances is very useful in the development of various types of technology.
Types and Types of Expansion
Expansion is divided into three types, namely expansion of solids, liquids, and gases. These three types will be explained as follows:
Expansion of solids
Expansion of solids is a type of expansion that occurs on an object, for example such as window frames, railroad tracks, and electrical cables. The window frame during the day looks curved, this happens because the object is experiencing expansion. Expansion of an object occurs in all parts of the object. Expansion of a solid is divided into three, namely length expansion, extensive expansion, and volume expansion.
a. Long expansion
Long expansion is increasing the length of an object because it receives heat. In the expansion of the length and width values are very small compared to the length value of the object. So width and thickness are considered absent. Examples of objects that only experience lengthy expansion are very small, very long wires.
Expansion of an object's length is influenced by several factors, namely the object's initial length, the coefficient of expansion length and the magnitude of temperature change. The length expansion coefficient of an object itself is influenced by the type of object or type of material. Mathematically the equation used to determine the length of the object after it is heated at a certain temperature is:
In the installation of the electrical network cable, the length of the power cable is overestimated, this is because the power cable has experienced a long expansion. The power cable will look tight in the morning and look loose in the afternoon. The cable has been expanded due to heat exposure from the sun. The tool used to investigate length expansion is musschenbroek. Expansion of an object's length is influenced by the object's initial length, the amount of temperature rise, and depends on the type of object.
b. Extensive expansion
Broad expansion is the increase in the size of an object because it receives heat. Extensive expansion occurs on objects that have a length and width, while the thickness is very small and is considered to be absent. Examples of objects that have extensive expansion is the glass window of the house. In a cold air the glass shrinks because the glass expansion coefficient is greater than the wood expansion coefficient. If the temperature rises, the glass will expand more than the wood frame so that the glass will look tightly attached to the wooden frame.
As in the case of broad expansion factors affecting the expansion of area are initial area, coefficient of expansion area, and temperature change. Because the actual expansion of the area is a length expansion in terms of two dimensions, then the coefficient of expansion of the area is equal to 2 times the coefficient of expansion of length. To determine the final area and volume increase the following equation is used:
c. Volume expansion
Volume expansion
Volume expansion is an increase in the size of an object's volume because it receives heat. Volume expansion occurs with objects of length, width and thickness. Examples of objects that have a volume expansion are cubes, water and air. Volume is another form of length in 3 dimensions because it is to determine the volume expansion coefficient equal to 3 times the length expansion coefficient. The equation used to determine the increase in volume and final volume of an object is:
Volume expansion
Liquid expansion
Expansion of liquid does not involve expansion or expansion, but is only known as expansion or volume expansion. The higher the temperature applied to the liquid, the greater the volume expansion. Expansion of liquid for each type of liquid is different, as a result, although initially the volume of liquid is the same, but after heating the volume becomes different. The expansion of liquid volume is related to the expansion of pressure due to an increase in temperature. The meeting point between liquid, solid, and gas forms is called a triple point.
Especially for water
Especially for water, the temperature increase from 0oC to 4oC does not increase in volume but instead shrinks. This exception is called the water anomaly. Therefore, at 4oC the water has the lowest volume. At 4oC the water occupies the smallest position so that at that temperature water has the largest density. So the water if the temperature is increased from 0 - 4oC will shrink, and if the temperature is increased from 4oC upward will expand. The relationship between volume and temperature in water is illustrated in the following graph:
Especially for water 2
Gas expansion
The gas expands when the temperature increases and will shrink if the temperature drops. In gas expansion there is no known expansion of long and wide expansion, there is only expansion of the volume of the gas. Expansion to gas is volume expansion which is formulated as follows:
V = V_o (1 + y.∆l)
Information:
y: volume expansion coefficient (1 / 273oC)
Expansion of the gaseous substance is divided into three types, namely expansion of the gas at a fixed temperature (isothermal), at a constant pressure (isobaric), and a fixed volume (isochhoric).
a. Gas expansion when isothermal
One example is a pump to fill the wind on a bicycle tire. Initially it will feel light (when removed), but over time it will become more severe. This is because when pressing the pump, it means the volume of the gas will decrease. Expansion of gas at a constant temperature applies Boyle's law which states that gas in a closed room whose temperature is kept constant, the product of pressure and volume of the gas is fixed. Based on this, it is formulated:
PV = Fixed or P_1 V_1 = P_2 V_2
Information :
P: pressure (atm)
V: volume (L)
b. Gas expansion when isobaric
Expansion of the gas at a constant pressure applies Gay Lussac's law, that is, the gas in a closed chamber with a constant pressure is maintained, the volume of the gas is proportional to the absolute temperature of the gas. In the form of an equation can be written as follows:
V1 / (T1) = V2 / T2
Information:
V: volume (L)
T: temperature (K)
c. Gas expansion when isochoric
Expansion of gas at a fixed volume applies Boyle-Gay Lussac's law that if the volume of gas in a closed room is kept constant, the gas pressure is equal to its absolute temperature. This law is formulated:
P1 / T1 = P2 / T2
Information:
P: pressure (atm)
T: temperature (K)
The Substance Expansion Concept
Application of the Expansion of Substance Substance in Daily Life
The principle of expansion of many substances is applied in everyday life. The following are a few examples of their application:
Installation of Window Glass
Installation of window glass also takes into account the expansion space for glass because the coefficient of expansion of the glass is greater than the coefficient of wood expansion where the glass is installed. This is very important to avoid bending the frame.
Railroad Connection Installation
Railroad connection must provide a gap between one rail bar and another rail bar. If the temperature rises, the railroad bar will expand until it will grow longer. With the expansion of inter rail space, there will be no pressure between rails which will result in the rail being bent.
Installation of the Iron Frame on the Pedati Wheel
The frame of the cart wheel in normal circumstances is made slightly smaller than its place so that it is not possible to be installed directly in its place. To install the frame, the iron must first be heated until it expands and its size will become larger than its place, making it easier to install the frame. When the temperature cools, the size of the frame shrinks again and is firmly in place.
Installation of Electric and Telephone Networks
Electrical or telephone network cables are installed loose from one pole to another so that when the air is cold the cable length will be slightly reduced and tightened. If the cable is not installed loose, then when there is a shrinkage the cable will be disconnected.