Lesson 1

• Solid • Liquid • Gas These states are defined by the arrangement and energy of their particles.

• Constant random motion • Collisions with each other and container walls • Negligible energy loss from collisions The kinetic theory explains how particles behave in different states of matter.

liquid Energy is required for particles to slip out of the ordered arrangement of a solid.

The energy required to change a substance from solid to liquid at its melting point This energy is necessary for overcoming the attractive forces in a solid.

Particles escape the attractive forces of other particles and enter the gas state This process can occur through evaporation or boiling.

The temperature at which the pressure of the vapor in the liquid equals the external pressure This allows particles to escape into the gas state.

The process of a solid changing directly to a gas without forming a liquid An example is dry ice, which undergoes sublimation.

Temperature changes over time as thermal energy is continuously added It illustrates phases like melting and boiling where temperature remains constant.

Matter with enough energy to overcome attractive forces within atoms, resulting in stripped electrons Most ordinary matter in the universe exists in the plasma state.

An increase in the size of a substance when the temperature is increased Substances also contract when they cool.

The liquid expands and rises as the temperature increases due to increased particle motion This is an example of thermal expansion in liquids.

Water expands as it cools from 4°C to 0°C This is due to the unique structure of water molecules.

Solids that do not have a specific melting point and soften over a range of temperatures Examples include butter and glass.

Substances that retain some ordered arrangement when they liquefy They are used in LCD screens and respond to temperature changes and electric fields.

The ability of a fluid to exert an upward force on an object immersed in it This force opposes the weight of the object.

Equal to the weight of the fluid displaced by the object This principle explains why some objects float while others sink.

The object’s density compared to the density of the fluid If the object’s density is less than the fluid’s, it will float.

The object’s density compared to the fluid’s density An object floats if its density is less than that of the fluid.

The steel block weighs much more than the wood block The gravitational force on the steel block is sufficient to make it sink, while the force on the wood block is not.

Mass per unit volume Density helps determine whether an object will float or sink.

Pressure applied to a fluid is transmitted throughout the fluid This principle explains how hydraulic systems work.

Pressure (Pa) = Force (N) / Area (m²) The SI unit of pressure is the pascal (Pa).

Pressure decreases This principle is crucial in understanding fluid dynamics.

The resistance of a fluid to flowing Fluids with high viscosity flow slowly, while those with low viscosity flow easily.