CHAPTER 9 HEAT Relationship between Temperature and Heat

CHAPTER 9 HEAT

Relationship between Temperature and Heat

Heat Flow

Heat Flow in Natural Phenomena

Sea breeze

Land breeze

Thermal Equilibrium • 2 objects in thermal contact can exchange heat energy between them. • the heat is transferred from the object with higher temperature to the object with lower temperature • when there is no net transfer of heat energy between objects, the objects are in thermal equilibrium. • the objects have same temperature

Principle of expansion and contraction of matter • How could I allow the metal bar to engage the gauge? • Is there any differences of level of coloured water in glass tube if I put the conical flask in a) hot water b) ice cube? • Why do I put the conical flusk in hot water? Why not cool water?

Principle of expansion and contraction in solid • Particles in solid vibrate in fixed position. When solid is heated, the particles vibrate faster and move further apart from one another. • The volume become higher because the solid expands. • If the solid is cooled, the particles vibrate slower and move one to one another. • This cause the volume decrease because the solid contracts.

Principle of expansion and contraction in liquid and gas • Particles in liquid and gases move freely. When liquid/gas is heated, the particles move faster and randomly. The distance between particles increase. • The volume become higher because the liquid and gas expands. • If the liquid/gas is cooled, the particles move slower and closer one to one another. • This cause the volume decrease because the liquid/gas contracts.

The uses of expansion and contraction of matter in daily life

Relationship between types of surface of object, and heat absorption and emission

• Bright colours (silver/white) do not absorb a lot of heat. Therefore the evaporation of fuel is reduced. • The ability of object to absorb or radiate heat depends on : – 1. type of surface – 2. colour of its surface

• When object absorb heats, its temperature increases • When object radiates heat, its temperature decreases • Dark and dull surfaces are better heat absorbers and radiators compared to white and shiny surfaces.

Heat concept on daily life • The Green Building Concept : reduce the effects of rapid development on the environment and our health. • It concern on : – Has high energy efficiency through the usage of solar energy or renewable energy – Has good water flow system, air circulation and lighting – Uses recycled materials