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Read About Heat: Transfer of Thermal Energy

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Heat: Transfer of Thermal Energy Video
WHAT IS HEAT: TRANSFER OF THERMAL ENERGY?

Heat is the transfer of thermal energy from one object to another. The transfer of thermal energy can occur by conduction, convection, or radiation. Some materials can store more energy than others.

To better understand Heat: Transfer of Thermal Energy…

WHAT IS HEAT: TRANSFER OF THERMAL ENERGY?. Heat is the transfer of thermal energy from one object to another. The transfer of thermal energy can occur by conduction, convection, or radiation. Some materials can store more energy than others. To better understand Heat: Transfer of Thermal Energy…

LET’S BREAK IT DOWN!

Heat, thermal energy, and temperature

Heat, thermal energy, and temperature

We all have a feel for what temperature is, and we even have a shared language to qualitatively describe temperature. The water in the shower feels warm. It’s cold outside. Don’t touch that, it’s hot! But defining temperature scientifically is not so easy. Basically, temperature is what the thermometer reads. To understand what that means, we have to think about substances at the macroscopic level (we can see it with our eyes) and at the particle level (atoms and molecules that make up the substance, which are too small to be seen with just our eyes).

Hot coffee in a cup may appear to be motionless, but the particles that are contained within it have kinetic energy. At the particle level, the atoms and molecules that make up the coffee are vibrating, rotating, and moving through the space of the cup. Stick a thermometer in the cup of coffee, and you will see evidence that the water possesses kinetic energy. The water’s temperature, as reflected by the thermometer’s reading, is a measure of the average amount of kinetic energy of the coffee molecules.

You know from experience that if you leave the hot cup of coffee sitting on the countertop over time it will cool down. On the macroscopic level, the coffee and the cup are transferring heat to their surroundings (i.e., the air and the countertop). The fact that the coffee’s temperature decreases over time is evidence that the average kinetic energy of its particles is decreasing. We refer to this transfer of energy from the coffee and the cup to the surrounding air and countertop as heat. Heat is the transfer of energy from hotter objects or regions to colder objects or regions.

Heat, thermal energy, and temperature We all have a feel for what temperature is, and we even have a shared language to qualitatively describe temperature. The water in the shower feels warm. It’s cold outside. Don’t touch that, it’s hot! But defining temperature scientifically is not so easy. Basically, temperature is what the thermometer reads. To understand what that means, we have to think about substances at the macroscopic level (we can see it with our eyes) and at the particle level (atoms and molecules that make up the substance, which are too small to be seen with just our eyes). Hot coffee in a cup may appear to be motionless, but the particles that are contained within it have kinetic energy. At the particle level, the atoms and molecules that make up the coffee are vibrating, rotating, and moving through the space of the cup. Stick a thermometer in the cup of coffee, and you will see evidence that the water possesses kinetic energy. The water’s temperature, as reflected by the thermometer’s reading, is a measure of the average amount of kinetic energy of the coffee molecules. You know from experience that if you leave the hot cup of coffee sitting on the countertop over time it will cool down. On the macroscopic level, the coffee and the cup are transferring heat to their surroundings (i.e., the air and the countertop). The fact that the coffee’s temperature decreases over time is evidence that the average kinetic energy of its particles is decreasing. We refer to this transfer of energy from the coffee and the cup to the surrounding air and countertop as heat. Heat is the transfer of energy from hotter objects or regions to colder objects or regions.

Transfer by conduction

Transfer by conduction

Warming and cooling is the macroscopic result of the particle-level motion. The mechanism in which thermal energy is transferred from one object to another object through particle collisions is known as conduction. During conduction, there is no net transfer of physical stuff between the objects. Nothing material moves across the boundary. The changes in temperature are explained as the result of the gains and losses of kinetic energy during particle collisions.

Think about what you observed (macroscopic view) when a copper bar with three chocolate bunnies on one end was heated on the opposite end. The copper bar consists of a collection of orderly arranged copper atoms that wiggle about a fixed position (particle view). As the copper atoms were heated on one end of the bar, they started to wiggle more vigorously. They bang into their neighboring copper atoms and increase their kinetic energy (wiggling). The process of energy transfer by means of direct contact between the particles is called conduction. The thermal energy is being conducted along the bar, and we see macroscopic evidence of that as it is transferred to the chocolate bunnies and they melt. (Note: The bar was heated using conduction and radiation.)