Application of the Principle of Expansion of Substances In Life

inernal energy Thermodynamics

Application of the Principle of Expansion of Substances In Life

Application of the principle of expansion of substances in life very much, including the field of transportation, development and technology. The principle of expansion can be applied in everyday life. Application and utilization of expansion principle is used in construction technology, railway and railway, bimetallic, drying, and installation of glass.

Application of the Principle of Expansion of Substances In Life

The principle of expansion of many substances applied in everyday life. The following are some examples of their implementation.

Application of the principle of expansion of substances in the field of construction

Construction experts and architects of buildings, bridges, and roads must know the nature of expansion and shrinkage of solids caused by temperature changes. Highway during the dry season many are damaged and cracked, due to the expansion of steel and its asphalt. Bridges and highways are made of steel that are connected to each other. During the grafting process, the construction expert must really take into account the expansion and shrinking properties of iron due to temperature changes, both during hot and cold evenings.

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In order that the steel joints are not curved due to expansion or depreciation, the steel joints are not fixed, together with each other. There should be enough cavities between the joints to avoid damage to bridges and roads caused by the expansion and depreciation of the steel.

Application of the principle of expansion of substances in the field of transportation technology

When we pass through the railway track we will see the rail curved. As with bridges and highways, steel used for railroads should be installed in hollow gaps to prevent railroad accidents caused by curved rails due to expansion of daytime warming.  

In addition to the railway, how to install railway wheel tires also use the principle of expansion. Before heated, the size of the tire diameter is slightly smaller than the diameter of the wheels. If the tire will be installed, it must be heated first in order to expand. Next, insert the tire into the wheel. Once inside, let the temperature drop. Once cool, the tire shrinks and will stick strongly to the wheel, without having to use a bolt. 

Application of the Principle of Expansion of Substances in Bimetal Technology

Bimetal is a tool consisting of two different coefficient values of expansion or different expansion velocities, bonded together. For example, bimetal made of iron and copper before heated the bimetal is in a state of straight and then after heated, the bimetal will curve toward the metal (iron) which the coefficient of expansion length is small or slow expansion. Furthermore, if the bimetal is cooled it will be curved toward a metal (copper) whose coefficient value of expansion is large or expands rapidly. 
Technological tools using bimetallic principles, including thermostats, automatic switches on irons, fire alarms, and thermometers. 

Thermostat

Luxury hotel rooms located in cool or cold areas, such as in the Peak-Bogor, Lembang-Bandung, or other areas have heat settings of the room. The thermostat model can be seen in the picture. When the air in the room is cold, the bimetal plate will shrink, straighten, and touch the plain metal plates so that the two ends of the plate touch each other.  

Read also :  Basic Concept of Thermodynamics

The touch between the two metal ends makes contact with an electric current, an incoming electric current and a closed heater circuit that ignites the heater so the room warms. Conversely, when the room is warm enough, the bimetal plate will expand and return to its original position, ie bend, no contact with electric current, electric current cut off, so the circuit is open, heater is disconnected, and the heating of the room is finished. 

Auto Switch in Automatic Iron

The temperature on the iron automatically, then it is called automatic iron. In the automatic iron there is a tool for automatically disconnecting and connecting electrical current, called an automatic switch. The working principle of automatic switch can be observed in the picture. When the temperature is high enough, the bimetal will curl away from contact (K), the electric current will break, the iron will cool down. When cold, the bimetal touches the contact (K), then the electric current flows back, so that the iron re-heat. 

Fire Alert Tool

If there is an increase in temperature around the device, the bimetal touches the contact so that an electric current flows towards the electric bell. The electric bell will ring, indicating a fire or heat. 

Bimetal thermometer

This thermometer is made of a curved bimetal. One end is clamped so it can not move. The other end is free to move and connected with a pointed needle. When the temperature rises, the bimetal becomes more curved. The pointer moves to the right. Conversely, when the temperature falls, the bimetal becomes more straight. The needle moves to the left.

How To Install Window Glass

Surely we have witnessed a carpenter when making window shutters or window frames. On the frame there is a gap that is made to place the glass. Glass is mounted on the part with the size of the glass is slightly smaller than the space or glass. This aims to maintain the safety of glass so as not to break, when experiencing expansion during the day or in the dry season. 

Thermodynamics Formulas

inernal energy Thermodynamics

Thermodynamics Formulas

Thermodynamics Formulas. The Steam engine is the first machine to be invented. It uses high-pressure steam to push a piston in a cylinder. The steam is produced by heating the water by using the flame from coal or gasoline. The Steam from the boiler is then delivered to a cylinder through a valve; this high-pressure steam will push the piston. When the piston is pushed to the edge of the cylinder through one edge and allows new steam pushes the piston back to its initial position. This cycle will keep on going as long as the steam is provided. The perpetual motion of the piston can be used to move another part of the engine.

Steam engine applies the concept of thermodynamics. And so do diesel engine, refrigerator, and air conditioner (AC); their working principles are the applications of thermodynamics concept.

Basic Concept Of Thermodynamics

Thermodynamics is a branch of physics that studies the relation of heat, mechanical energy, and its conversion from one into the other. Before studying thermodynamics, we first need to understand the definition of system and environment besides the terms of equilibrium, heat, work, and energy.

1. System and Environment

the system can be defined as a separated part which becomes the point of observation. A system can be a room, body, quantity of matter, etc. Environment or surroundings can be defined as anything outside the system which may influence the state of the system directly.

2. Equilibrium 

There is term "equilibrium" in thermodynamics. There are three types of equilibrium in thermodynamics, i.e. mechanical, chemical, and thermal equilibrium. when the conditions for the equilibrium to take place are fulfilled, then the system is said to be in a thermodynamic equilibrium. In that state, there is no tendency of state alteration in either system or its environment.

3. Definition of Heat

Heat is energy which moves due to the temperature difference between the system and its environment. The system can release heat to its environment, and on the contrary, the environment can also send out its heat to the system.

4. Definition of work thermodynamics

Figure 8.2 shows liquid in a cylinder equipped with a freely moving piston. If the cylinder's cross-section is A and the pressure given by the piston is P, then the force produces is F = PA. When the piston moves outward at a distance of dx, the work dW performed by the force F is:

dW = F dx = PA dx

However, A dx = dV or the volume change and so we have

dW = P dV

During the volume change from V₂ to V₁, the pressure P is constant as shown in Figure 8.3, and so the work performed by the system is

W = P(V₂ - V₁) 

Therefore, in every process with constant volume (V₁ = V₂), the work performed by the system in equal to zero. If V₂ > V₁ it means the work is performed by the system; its value is positive. Inversely, If V₂ > V₁, it means the work is given to the system; its value is negative.

Example :

A certain gas undergoes expansion at a constant pressure of 5 atm (1 atm = 10⁵ N/m²). Its initial volume was 300 L and the volume gets doubled soon after the expansion. Determine the work done by the gas.

Answer :

P = 5 atm = 5 x 10⁵ N/m²

V₁ = 300 L = 0,3 m³
V₂ = 2V₁ = (2) (0,3 m³ ) = 0,6 m³
W = P ΔV
 W =  P(V₂ - V₁)  = (5 x 10⁵ N/m²) ( 0,6 m³ - 0,3 m³) = 1,5 x 10⁵ J

Internal Energy

Every particle in a system always moves. Given that kinetic energy of each particle in a system is E_k, and the total number of particle in the system is N, the internal energy (U) of the system can then be expressed by:

U = NE_k

Internal energy is conservative; meaning that its value does not depend on the path or process was taken; it depends only on the initial and the final state of the system. Internal energy is a characterized state of gas which can not be measured directly. The thing that can be measured directly is the change of internal energy (ΔU); it is when the system changes from its initial state (U₁) to its final state (U₂). Internal energy is a state function which the change is formulated by 

ΔU = U₂ - U₁

 Thermodynamic Process

Process or the change of thermodynamic state can be classified into two, i.e irreversible and reversible processes. The irreversible process is a spontaneous process in one direction; it can not occur in the reverse direction. The reversible process is a process of which the direction can be reversed. The reversible process is an equilibrium process. The system that undergoes a reversible process will always be in a state of thermodynamic equilibrium.

The thermodynamic process can be in the form of expansion, compression, heating, or cooling processes. The thermodynamic process can take place in a state of isothermal, Isochoric, isobaric, or adiabatic processes.

1. Isothermal

An isothermal process is a process of state alteration of gas which takes place at constant temperature.

This process agrees with Boyle's law, which states that the value of PV is constant at a fixed temperature or more clearly stated by the general equation of ideal gas, PV= nRT. The work performed received by the system can be obtained by calculating the area under the P-V curve.

In fact, the work W in the equation above has the same meaning with the area below the curve on P-V graph. Suppose you have learned the integral concept as the area below the curve of a function, you certainly understand that formulation.

2. Isochoric

Icochoric process is a process of the state alteration of gas which takes place at constant volume.

 Isochoric process agrees with Charles' law, which states that the value of P/T is constant at a fixed volume. What is the value of work in the isochoric process? By remembering the work definition as the area below the curve of P-V graph, you can conclude that the work in isochoric process is zero (W=0). It can also be understood that there is no volume change, therefore we have ΔV = 0, W = ΔV = 0.

3. Isobaric

Isobaric process is a process of gas state alteration which takes places at a constant pressure.

Isobaric process agrees with Gay-Lussac's law, which states that the value of V/T is constant for a fixed pressure. How much work is involved in the isobaric process? By noticing the curve of P-V graph, you can determine the value of the work as an area below it.
W = P(V₂ – V₁) = P ΔV
The process of gas state alteration of gas state alteration in a steam engine's boiler is usually isobaric. The steam volume addition process in the boiler is carried out without changing the pressure inside it.

Thermodynamics Eequation

1)  A thermodynamics process without any heat transfer between the system and its surroundings is called........
a.  Adiabatic
b.  Isochoric
c.  Isobaric
d.  Isothermal
e.  Isovolume

2) An amount of 2 x 10^-3  mol gas expands isothermally from V₁ = 20 cm³ to V₂ = 50 cm³ at the temperature of T = 300 K. If the universal gas constant is R = 8.3 J/mol.K, the work performed in the system is..........
a.  4.56 x 10³ Joule
b.  4.56 x 10² Joule
c.  4.56 x 10¹ Joule
d.  0.456 x 10^-1 Joule
e.  0.456  Joule

3) A kind of gas in a cylinder has an initial volume of  20 cm³. The gas experiences expansion at a constant pressure of 2 x 10⁴ N/m² in a way that its volume becomes 40 cm³; the work performed is.....
a.  0.2 Joule
b.  0.3 Joule
c.   0.4 Joule
d.  0.5 Joule
e.  0.6 Joule

4) An amount of 1.5 m³ helium gas at a temperature of 27^oC is heated isobarically to 87^oC. If the pressure of the helium gas is 2 x 10⁵ N/m², its external work will be .........
a.  60 kJ
b.  120 kJ
c.  280 kJ
d.  480 kJ
e.  660 kJ

5)  A mol of ideal gas at a temperature of T is in a cylinder equipped with the frictionless piston. The gas is then heated at constant pressure in a way that its volume becomes fourth of its initial. If R is the universal gas constant, the work performed by the gas is..........
a.   RT/4
b.   RT ln 4
c.   6RT
d.   4RT
e.   3RT

You Need To Know

Refrigerator in an electronic appliance we find regularly in our everyday life. The working principle of the refrigerator is making use of the second law of thermodynamics. The room inside the refrigerator acts as a cold reservoir whose temperature is  T_C, whereas the room outside the refrigerator act as the hot reservoir whose temperature is Th,

The heat in the cold reservoir is generated by the foods, drinks, or other things in the refrigerator. This heat will be removed and delivered to the outside air around the refrigerator. The electric energy is needed to flow the heat from the cold reservoir to the hot one. The electric energy used to operate the refrigerator is provider by our household electric installation. We buy this electric energy from a provider. In order to save the electric cost, it is necessary for us to chose the high effectiveness refrigerator.