Liquids vs. Pressure of Solids

What's the Difference?

Liquids and pressure of solids are two distinct concepts in physics. Liquids are a state of matter characterized by their ability to flow and take the shape of their container. They have a definite volume but no definite shape. On the other hand, pressure in solids refers to the force exerted on a given area due to the weight of the object or the external forces acting on it. Solids have a fixed shape and volume, and pressure is distributed evenly throughout the object. While liquids exert pressure as well, it is not as easily quantifiable as in solids due to their ability to flow and change shape.


AttributeLiquidsPressure of Solids
State of MatterLiquidSolid
ShapeTakes the shape of the containerRetains its own shape
VolumeDefinite volumeDefinite volume
Intermolecular ForcesWeaker intermolecular forcesStronger intermolecular forces
Arrangement of ParticlesRandom arrangementTightly packed arrangement
Motion of ParticlesParticles move freelyParticles vibrate in fixed positions
FluidityFlows easilyDoes not flow
Surface TensionHas surface tensionDoes not have surface tension
ViscosityVaries in viscosityDoes not have viscosity

Further Detail


Liquids and solids are two fundamental states of matter that exhibit distinct properties and behaviors. While liquids flow and take the shape of their container, solids maintain a fixed shape and volume. In addition to these macroscopic differences, there are several other attributes that differentiate liquids and the pressure of solids. This article aims to explore and compare these attributes in detail.

Intermolecular Forces

One of the key differences between liquids and solids lies in the strength of their intermolecular forces. In liquids, the intermolecular forces are weaker compared to solids. This allows the particles in a liquid to move more freely, resulting in their ability to flow. On the other hand, solids have stronger intermolecular forces, which hold the particles tightly together in a fixed arrangement. This gives solids their rigidity and resistance to flow.

Shape and Volume

As mentioned earlier, liquids take the shape of their container, while solids maintain a fixed shape and volume. This is due to the difference in the arrangement of particles in each state. In a liquid, the particles are loosely packed and can move past each other, allowing the liquid to flow and take the shape of its container. In contrast, the particles in a solid are tightly packed and arranged in a regular pattern, resulting in a fixed shape and volume.


Another attribute that distinguishes liquids and solids is their compressibility. Liquids are generally considered to be incompressible, meaning their volume cannot be significantly reduced by the application of pressure. This is because the particles in a liquid are already close together, and further compression would require overcoming the repulsive forces between them. On the other hand, solids can be compressed to some extent under high pressure. However, the compressibility of solids is still significantly lower compared to gases.


Viscosity is a measure of a fluid's resistance to flow. Liquids typically exhibit higher viscosity compared to solids. This is because the particles in a liquid have more freedom to move past each other, resulting in greater internal friction. As a result, liquids flow more slowly and have a higher resistance to deformation. Solids, on the other hand, have lower viscosity due to their rigid structure, which allows them to resist deformation and flow.

Pressure in Solids

While liquids are not directly associated with pressure, solids experience pressure due to the external forces applied to them. Pressure in solids is defined as the force per unit area exerted on the surface of the solid. When a solid is subjected to an external force, the force is distributed over the entire surface area, resulting in pressure. The magnitude of the pressure depends on the force applied and the area over which it is distributed. This pressure can cause deformation or structural changes in the solid, depending on its elasticity.

Phase Transitions

Liquids and solids also differ in their response to changes in temperature and pressure. Liquids undergo phase transitions, such as boiling or freezing, at specific temperature and pressure conditions. These transitions involve a change in the arrangement and motion of the particles, resulting in a conversion between liquid and gas or liquid and solid states. Solids, on the other hand, can undergo phase transitions such as melting or sublimation, where they change from a solid to a liquid or gas directly, without passing through an intermediate liquid phase.

Thermal Expansion

Thermal expansion is the tendency of matter to change in volume in response to a change in temperature. Both liquids and solids exhibit thermal expansion, but the extent of expansion differs between the two states. Liquids generally have a higher coefficient of thermal expansion compared to solids. This means that liquids expand more significantly with an increase in temperature compared to solids. The expansion of liquids is due to the increased kinetic energy of the particles, which causes them to move further apart. Solids, on the other hand, have a lower coefficient of thermal expansion, resulting in less noticeable changes in volume with temperature variations.


In conclusion, liquids and solids possess distinct attributes that set them apart from each other. Liquids flow and take the shape of their container, while solids maintain a fixed shape and volume. Liquids have weaker intermolecular forces, higher viscosity, and higher thermal expansion compared to solids. On the other hand, solids have stronger intermolecular forces, lower viscosity, and lower thermal expansion. Additionally, solids experience pressure due to external forces, while liquids do not have a direct association with pressure. Understanding these attributes helps us comprehend the behavior and properties of liquids and solids, contributing to various scientific and practical applications.

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