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Heat is the movement of thermal energy from one body to another. Thermal energy comes from the motion of tiny particles inside matter.
When the particles move fast, the temperature rises, and the body feels hot. When they move slowly, the temperature remains low, and the body feels cool.
Now imagine we have two bodies: one hot and one cold. The moment they touch, something interesting happens.
The fast-moving particles in the hot body bump into the slower particles in the cold body, causing energy to flow from the hot body into the cold one.
Heat always moves from the warmer body to the cooler body, never the other way around.
This continues until both bodies reach the same temperature and come to a balance point.
When an ice cube is dropped into warm water, the ice warms up, the water cools down, and eventually both reach the same temperature. This exchange of energy happens through heat transfer.
Heat moves in three ways: conduction through solids, convection through moving fluids, and radiation through waves.
