This article answers the question- Is length extensive? We all must be knowing the meaning of length, it is the measure of any object from one end to another.
The term extensive refers to quantities that are dependent on mass. Their value changes when the value of mass changes in magnitude. In this article we shall discuss about extensive properties and then discuss whether the length is extensive or intensive. We shall also discuss about examples of extensive properties and intensive properties.
What is length?
Length is a measurement of objects two dimensional size from one end to another end. The SI units of length is m.
Terms like breadth and height also denote the measurement of object. Length can be said as the longest side of the object. Length depends on the mass of object as when we consider more mass we are directly referring to a greater length.
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What is an extensive property?
Some properties depend on the mass content while some properties do not. The properties that are affected by the mass content in the system are called as extensive properties.
The extensive properties when divided with another extensive property will give rise to an intensive property that means the ratio will be intensive. In further sections we will discuss about different examples of extensive properties and intensive properties.
Is length extensive?
Yes. Length is an extensive property as the definition of extensive property states a condition that they should be mass dependent.
When we consider more matter then we are directly referring that the length of the object is also more. In simple terms when we cut an object into half, the value of mass reduces to half and hence the value of length also becomes half. Hence it is safe two conclude that length is an extensive property.
How is length extensive?
Length is an extensive property as its value will change when the value of mass will change. Let us see the example given below to get a clear picture.
Let us consider a block of wood of a certain mass, m. When we cut that block of wood into equal halves, each block will have a mass equal to 0.5m. We can visually observe that the length of the blocks also reduced by half. We conclude that length is an extensive property as its value depends on the mass content in the system.
When is length extensive?
Length is extensive only when the density of object taken into consideration is constant. If the density is variable then there is a chance that the length of the object will not change even if the value of mass changes.
For example, if we cut a chewing gum into half then stretch the other half, we will observe that it gains it original length at an expense of breadth. Here the length is not exactly dependent on mass as we can easily gain the length by stretching out the chewing gum.
Extensive property example
The list below shows the examples of extensive properties –
- Mass – Mass itself is the reference that decides whether a property is intrinsic or extrinsic. So we can say that mass is also an extrinsic property as it is quantity or mass dependent.
- Volume – When we are considering a system having incompressible matter then we can say that volume is an extrinsic property. When we split the system into two parts, the volume also gets divided into half meaning that volume is a mass dependent property.
- Length– Length is an extrinsic property and the reason is already discussed in the above sections. The length is directly related to matter as when we are referring to length of an object we are referring to the quantity of matter present in the system. When the quantity reduces the length will also reduce.
- Weight– Weight means mass multiplied by the value of g that is 9.8 m/s. When we reduce the mass then automatically weight will also reduce. When we talk about reducing weight, we are indirectly referring to reduce the mass of system.
- Entropy – Entropy is a measure of randomness. This is a very important term used in thermodynamics. When it is divided with the mass then a new term is defined known as specific entropy. This property is an intensive property and is discussed in the next section.
- Energy– Energy or enthalpy of a system is an extrinsic property. Greater is the mass content inside the system greater will be the value of enthalpy. Like entropy, enthalpy becomes specific enthalpy when divided with mass which is an intensive property.
Intensive property example
The list given below discusses about the examples of intensive properties-
- Temperature – Temperature can be called as an intensive property as it has no affect of mass on it. Even if the system is divided into two halves, the temperature of both the halves will be same as that of original system.
- Density – Density of the system does not change even if we divide the system into two parts. This means that density is an intensive property. Actually the reason behind this is that density is the ratio of two extensive properties and ratio of two extensive properties is always an intensive property.
- Pressure – Pressure of the system remains the same even if we divide the system into two halves. Thus we can say that pressure of the system is an extrinsic property.
- Specific entropy – Specific entropy is the ratio of two extrinsic properties. Thus it is an intensive property. The specific entropy is simply the entropy divided by the mass content.
- Specific enthalpy – Similar to specific entropy, specific enthalpy is also an intensive property as it is a ratio of two extrinsic properties.
We have discussed about extrinsic and intrinsic properties. We conclude that length is an extrinsic property as the value of length depends on the mass content of the system. When we are talking about the length, we are referring to the mass content as when the mass content will reduce the length will also reduce.