Heat & Temperature

Understanding heat, temperature, and thermal energy transfer

Topics

How does a heat pump work?

A heat pump works by using a refrigerant cycle to transfer heat from a cooler area to a warmer area, opposite to natural heat flow. It compresses refrigerant to heat it, then expands it to cool it, moving heat against the temperature gradient using mechanical work.

How does heat transfer work?

Heat transfers through three mechanisms: conduction (direct contact between objects), convection (movement of fluids), and radiation (electromagnetic waves). Heat always flows from hotter objects to colder objects.

What is absolute zero?

Absolute zero is the theoretical lowest possible temperature, at which particles have minimal motion and no thermal energy can be removed. It's defined as 0 Kelvin (-273.15°C or -459.67°F) and represents the point where entropy reaches its minimum value.

What is heat?

Heat is energy that transfers from one object to another due to a temperature difference. It flows from hotter objects to colder objects until thermal equilibrium is reached.

What is temperature?

Temperature is a measure of the average kinetic energy of particles in a substance. It indicates how hot or cold something is and determines the direction of heat flow—heat flows from higher temperature to lower temperature.

What is the difference between heat and temperature?

Heat is energy being transferred between objects, while temperature measures how hot or cold something is. Heat is the total energy transferred, while temperature measures the average kinetic energy of particles.

What is thermal conductivity?

Thermal conductivity is a material property that measures how well a material conducts heat. Materials with high thermal conductivity (like metals) transfer heat quickly, while materials with low thermal conductivity (like wood or insulation) transfer heat slowly, making them good insulators.

Why do different materials have different specific heat?

Different materials have different specific heat because they have different molecular structures and bonding. Materials with stronger bonds and more complex molecular structures require more energy to increase temperature, giving them higher specific heat. Water has unusually high specific heat due to hydrogen bonding.

Why does metal feel cold?

Metal feels cold because it conducts heat away from your skin very efficiently. Even at room temperature, metal quickly transfers heat from your warmer hand, making it feel cold compared to materials that conduct heat poorly.

Why does pressure affect boiling point?

Pressure affects boiling point because boiling occurs when vapor pressure equals atmospheric pressure. Higher pressure requires higher temperature to reach the vapor pressure needed for boiling, so water boils at higher temperatures under high pressure and lower temperatures under low pressure.