Heat and work are two different ways of transferring energy from one system to another. Heat is the transfer of thermal energy between systems, while work is the transfer of mechanical energy between two systems.

The relationship between the internal energy of a system and its heat and work exchange with the surroundings is: E = q + w (The form of work will be restricted to gaseous, PV-type for this discussion.)

The core difference is that heat deals with thermal energy, whereas temperature is more concerned with molecular kinetic energy. Heat is the transfer of thermal energy, whereas temperature is a property the object exhibits.

Heat is the total kinetic energy and potential energy obtained by molecules in an object. Temperature is the average K.E of molecules in a substance. Heat flows from hot body to cold body. It rises when heated and falls down when an object is cooled down.

No in the sense that a material must maintain an identical chemical makeup and then change from one phase to another, not all solids have a melting point. Changing from a solid to a liquid state such as when a metal, wax or ice is heated to its melting point, or the specific temperature at which melting occurs.

When a solid is heated the particles gain energy and start to vibrate faster and faster. Further heating provides more energy until the particles start to break free of the structure. Although the particles are still loosely connected they are able to move around. At this point the solid is melting to form a liquid.

Cooling a solid decreases the motion of the atoms. A decrease in the motion of the atoms allows the attractions between atoms to bring them a little close together.

When a substance is heated, it gains thermal energy. Therefore, its particles move faster and its temperature rises. When a substance is cooled, it loses thermal energy, which causes its particles to move more slowly and its temperature to drop.

Freezing occurs when a liquid is cooled and turns to a solid. Eventually the particles in a liquid stop moving about and settle into a stable arrangement, forming a solid. The boiling and condensation point of a substance is defined as the temperature above which, the substance is gas and below which, it is liquid.

Most materials contract when they are cooled and get bigger when they are warmed up. But some substances do the opposite by shrinking in certain directions as they are heated and expanding when cooled.

When the particles of water are heated, it tends to move faster which expands the liquid. While when water is cooled , the particles tend to get slower. Also when water is cooled it will undergo into Freezing in which liquid is turned into solid.

When heat is added to a substance, the molecules and atoms vibrate faster. As atoms vibrate faster, the space between atoms increases. The motion and spacing of the particles determines the state of matter of the substance. The end result of increased molecular motion is that the object expands and takes up more space.

Heating can cause an irreversible change. For example you heat a raw egg to cook it. The cooked egg cannot be changed back to a raw egg again.

particles, gases can be compressed. You have seen that adding heat energy makes molecules move faster and that removing heat energy (cooling) makes molecules slow down. Heating and cooling affect all states of matter—solids, liquids, and gases. Or when cooled, a gas can become a liquid and then a solid.

Things That Are Not Matter

• Time.
• Sound.
• Sunlight.
• Rainbow.
• Love.
• Thoughts.
• Gravity.
• Microwaves.

• Bose–Einstein condensate.
• Fermionic condensate.
• Degenerate matter.
• Quantum Hall.
• Rydberg matter.
• Rydberg polaron.
• Strange matter.
• Superfluid.