"Soft materials" are materials that can be compressed. Cotton, rubber, and sponge are a few examples. Hard materials are materials that cannot be compacted. Steel, rock, and iron are among examples.
Because soft materials can be compressed, they can be made into sheets that can be used in various products. For example, the sheet metal in an automobile is mostly made from steel which is a hard material. But it can be made more workable by adding some softeners such as linseed oil or zinc chloride. These additives make the metal pliable enough to be formed into shapes with other metals.
There are several types of soft materials. Rubber, for example, is a polymer (a large molecule composed of many smaller molecules called atoms) that is solid at room temperature. It can be softened by either adding heat or coldness and made more workable. Sponges are structures made out of cells separated by membranes; they are found in animals' bodies and also used as sponges for absorbing liquids.
Cotton is the seed pod of the cotton plant (Gossypium hirsutum). The seeds are covered with fibers (trichomes) that are resistant to moisture, heat, and pests. However, like other soft materials, cotton can be softened by treatment with chemicals or heat.
Hard materials are those that cannot be readily crushed, cut, deformed, or scraped. Examples include iron and glass. "Soft materials" are those that can be readily crushed, sliced, bent, or scraped. Examples are sponges and cotton.
Hard materials can be harder than soft ones (for example, granite is harder than clay). But hardness by itself is not enough to describe the properties of materials like wood, metal, or plastic. Those properties must also be flexible for them to be useful in tools and products.
The terms hard and soft have different meanings for tools vs products. Tools are designed to be hard so they don't break easily; products are expected to be soft so they feel pleasant when touched. Products may contain both hard and soft items (like a knife blade), while tools usually only have one type of material (usually hard for knives).
Hardness can be increased by using a higher quality material or adding more layers of hard material. Softness can be decreased by using a lower quality material or removing some of the hard material layers. These modifications are called "hardening" or "softerizing" the tool or product, respectively.
Hard materials include stones, metals, and other hard substances. Soft materials include fabrics, leather, tissues, and other soft substances.
Examples of soft materials include cotton and rubber.
Hard materials are used in many tools, such as hammers and plows. Soft materials are used in items where strength is more important than hardness, such as clothes and tires. The quality of a material determines how easily it can be worked with its corresponding tool or object.
There are several other properties of materials that determine how we use them. For example, colorants can be added to materials to make them easier to identify or absorb moisture from the air. Conductors like copper help materials transfer heat quickly while insulators like plastic stop heat from flowing through them.
The purpose of a material is also relevant when determining what kind it should be for specific uses. For example, wood is used for tools because of its hardness; wool is used for clothing because of its warmth. A substance may have more than one purpose in life: steel is used for tools because of its hardness and toughness, but also acts as an oxidizer which makes it useful as a building material too!
Finally, the form in which a material is sold determines how it is used by consumers.
At room temperature, soft materials are those that may be easily deformed by thermal pressures or thermal fluctuations. Liquids, polymers, foams, gels, colloids, granular solids, and most soft biological materials are examples of soft materials. As temperatures approach the melting point or boiling point of hard materials such as salt or iron, they become softer yet. Soft materials can be damaged by stresses at too high a temperature, so they must be treated with care when being heated in contact with other objects or materials.
The properties of materials depend on their chemical composition. All materials are made up of molecules (atoms or groups of atoms) that attract each other through electrostatic forces ("electrons") or magnetic forces ("magnetism"). These molecules can be solid, liquid, or gas. A material is called a "solid" if its molecules are fixed in place, like rock powder or glass beads. A solid can also be called a "polymer" if it is made up of long chains of repeating units called "monomers". Monomers join together to form long chains, and these chains fold back on themselves to make more complex shapes like ropes or sheets.
A liquid is a smooth, flowing solid that loses its shape when pressed from all sides. Liquids may appear clear or cloudy depending on the type of particle that is visible under magnification.
Soft materials require less stress (or opposing force per unit area) to experience the same amount of strain (or deformation). Something that is soft can be readily distorted. When you push on a soft object, it distorts rather than resists your push.
Something that is hard cannot be distorted; instead, it cracks or breaks under pressure. Hard objects do not become softer when stressed; they just break down. Soft things may get broken up into smaller pieces, but they tend to re-form into their original shape once the stress is removed.
The opposite of soft is hard. Hard objects such as rocks resist distortion under pressure while soft objects like balloons or marshmallows behave like fluids and resist compression. A material's hardness determines how much stress it can withstand before breaking.
So, hard things don't change shape when pressured, whereas soft things do. This seems like a good explanation until you think about balloons. Balloons are made of rubber or plastic, which are both types of soft materials. However, balloons do not retain their original shape after being deflated, which shows that they distort under pressure.
This proves that something doesn't have to be hard to be soft.
Ceramics, concrete, some metals, and superhard materials are common examples of hard matter, which can be compared with soft matter. The term "hard material" is somewhat misleading, because many hard substances are quite fragile and could be destroyed by a slight touch. For example, glass is hard but brittle; sand is hard but powdery. A diamond is the hardest substance known to man; it is also very brittle.
Hardness is a measure of resistance against penetration. Hard materials such as ceramics or diamonds are difficult to drill or cut with sharp tools because the tip of the tool gets quickly dulled down. Soft materials like cotton or wool feel pain when they are scratched too deeply. The harder a material is, the more damage it can withstand before breaking.
In physics, hardness relates to the resistance of a material to abrasion. As we will see, this definition applies not only to physical objects but also to biological materials such as teeth or coral. In biology, hardness is used to describe the resistance of organisms to physical injury such as bites from predators or the force of water during floods. Animals with thick shells or tough skin tend to be harder than those without such protection.