Think about ice melting into water, and then water being heated up and turning into steam. Similarly, when a material changes phase, it only changes physically the substance is still the same. A piece of metal may be heated in a fire until it glows, but the metal is the same material before heating and after cooling. The wood itself has not changed during sanding to become a new material, only the texture of the surface changed. For instance, a block of wood may feel rough when you run your finger across it but rubbing the wood with sandpaper smooths the surface so it no longer feels rough. A change in the texture of a substance is a change in the way it feels.
Types of some physical changes are texture, shape, temperature, and a change in the state of matter.
What Is a Physical Change? In a physical change, the material involved in the change is structurally the same before and after the change. Chemical changes, on the other hand, are not reversible: A log burned in a fire turns to ashes, but the ashes cannot be changed back into a log. Physical changes in matter are often reversible: An ice cube can melt into liquid water, and then the liquid water can be frozen back into an ice cube. Matter is capable of undergoing changes, which are classified as either physical or chemical.
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