Principles of Heat Transfer and Matter Transformation

Mechanisms of Heat Transfer

Conduction

The process by which heat passes through a solid is called conduction. In this process, there is no mass transport of heat energy. It only occurs when different parts of a body are at different temperatures.

Convection

Convection is the process by which heat is transferred through a fluid by the movement of the fluid itself. For example, as water is heated, the warmer, less dense portion rises while the cooler, more dense portion sinks, establishing a convection current.

Radiation

Radiation is the process by which an energy source emits and transmits energy in the form of electromagnetic waves, which do not require a material medium to travel. Any body with a temperature above 0 Kelvin (absolute zero) emits radiation.

Climate Change and Energy

Climate change is driven by an increase in greenhouse gases, largely due to the excessive use of non-renewable fossil fuels such as oil, wood, natural gas, and coal.

Physical vs. Chemical Phenomena

Physical Phenomena

Physical phenomena are events that occur without transforming matter, meaning the original substance is retained. In these cases, the substance remains the same, even if its form changes. Examples include:

• Changes of state (e.g., melting ice)
• Kicking a ball
• Tearing a piece of paper

Chemical Phenomena

Chemical phenomena are events that occur with a transformation of matter, meaning the original substance is not retained and new substances are formed. Examples include:

• Breathing
• Digestion
• Burning paper or any other chemical reaction

Explanations and Classifications

1. This is because wood is a poor conductor of heat, while metal is a good conductor.
2. (Question missing)
3. Water feels colder because while the sun's radiation is the same for both water and land, their specific heat capacities differ. Water requires more energy to heat up than land does.
4. This is called the greenhouse effect. It occurs naturally in a planet's atmosphere, which has the ability to retain some of the sun's rays reflected from the surface. Natural greenhouse gases include water vapor, ozone, carbon dioxide, oxides of nitrogen, and methane. The atmosphere also reflects some of the natural radiation emitted by the Earth.
5. B and D
6. Classification of phenomena:
   • Lightning: Physical
   • Melting ice: Physical
   • Decomposition of flesh: Chemical
   • Dropping a pot: Physical
   • Baking a cake: Chemical
   • Evaporation of alcohol: Physical
   • Decomposition of ozone: Chemical
   • Breathing: Chemical
   • Oxidation of iron: Chemical
   • Combining hydrogen and oxygen: Chemical