DENSITY OF WATER GCM FREE

If both blocks are dropped in a tank of water, why does the wood float and the brass sink ( Figure 14.3)? This occurs because the brass has a greater density than water, whereas the wood has a lower density than water. Suppose a block of brass and a block of wood have exactly the same mass. Plasma will not be discussed in depth in this chapter because plasma has very different properties from the three other common phases of matter, discussed in this chapter, due to the strong electrical forces between the charges. At high temperatures, molecules may disassociate into atoms, and atoms disassociate into electrons (with negative charges) and protons (with positive charges), forming a plasma. There exists one other phase of matter, plasma, which exists at very high temperatures. In this chapter, we generally refer to both gases and liquids simply as fluids, making a distinction between them only when they behave differently. When placed in an open container, gases, unlike liquids, will escape. This makes gases relatively easy to compress and allows them to flow (which makes them fluids). In contrast, atoms in gases are separated by large distances, and the forces between atoms in a gas are therefore very weak, except when the atoms collide with one another. Because the atoms are closely packed, liquids, like solids, resist compression an extremely large force is necessary to change the volume of a liquid. When a liquid is placed in a container with no lid, it remains in the container. That is, liquids flow (so they are a type of fluid), with the molecules held together by mutual attraction.

DENSITY OF WATER GCM FREE

This occurs because the atoms or molecules in a liquid are free to slide about and change neighbors. Liquids deform easily when stressed and do not spring back to their original shape once a force is removed. A gas must be held in a closed container to prevent it from expanding freely and escaping. (c) Atoms in a gas move about freely and are separated by large distances. Forces between the atoms strongly resist attempts to compress the atoms. (b) Atoms in a liquid are also in close contact but can slide over one another. Gases have neither specific shapes nor definite volumes, since their molecules move to fill the container in which they are held ( Figure 14.2).įigure 14.2 (a) Atoms in a solid are always in close contact with neighboring atoms, held in place by forces represented here by springs. Gases are not bonded to neighboring atoms and can have large separations between molecules. The distance between molecules is similar to the distances in a solid, and so liquids have definite volumes, but the shape of a liquid changes, depending on the shape of its container. The molecules in a liquid are not locked in place and can move with respect to each other. Like solids, the molecules in a liquid are bonded to neighboring molecules, but possess many fewer of these bonds. (Shearing forces are forces applied tangentially to a surface, as described in Static Equilibrium and Elasticity.) Characteristics of FluidsĬonsidered to be fluids because they yield to shearing forces, whereas solids resist them. Even a large force produces only small displacements in the atoms or molecules of the lattice, and the solid maintains its shape. The structure of this three-dimensional lattice is represented as molecules connected by rigid bonds (modeled as stiff springs), which allow limited freedom for movement. In some cases, the force between molecules can cause the molecules to organize into a lattice as shown in Figure 14.2. Although true solids are not incompressible, it nevertheless requires a large force to change the shape of a solid. Solids will take a form determined by the nature of these forces between the molecules. The atoms or molecules in a solid are in close proximity to each other, and there is a significant force between these molecules. Solids are rigid and have specific shapes and definite volumes.

We will look at each of these phases in detail in this section. Matter most commonly exists as a solid, liquid, or gas these states are known as the three common phases of matter.

Calculate force given pressure and area.

Explain the relationship between pressure and force.Define pressure and its related SI units.Compare and contrast the densities of various substances.

Define density and its related SI units.

Distinguish between compressible and incompressible materials.

Describe the characteristics of the phases of matter at the molecular or atomic level.

By the end of this section, you will be able to:

Density of water gcm