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Objectives:
Objectives:
Identify and analyze the relationship and differences between energy, heat, and temperature.
Response correctly in the practice assessment about energy.
Realize the benefit of heat and temperature in daily life.
Introduction
Introduction
Think about your day for a moment. When you wake up and stretch, you're using energy from the food you ate the day before. When you run to catch the bus, that’s energy at work in your muscles. Ever notice how your phone runs out of battery after a while? That’s because energy flows through everything—your phone, your body, your bike, and even the lightbulbs in your room. In physics, energy is what makes things move or change. It's stored in different forms, like heat, light, motion, and even in the food you eat! From the moment you wake up to the moment you go to bed, energy is powering your world-changing it, moving it, and making it all happen.
What is energy?
What is energy?
Energy is the capacity to do work or cause change. It exists in various forms, such as kinetic, potential, thermal, and electromagnetic, and can be transformed from one form to another but is always conserved.
Internal energy, in the other hand, is the total energy of the particles in a body. It includes the energy associated with motion and interactions between particles. (the image below is the representation moving particle)
Real Life Example
Real Life Example
Imagine you’re riding a skateboard down a hill. As you start at the top, you have potential energy—energy stored because you're high up. As you roll down, that potential energy changes into kinetic energy, the energy of motion. Now, think about how your body feels after you stop. You might notice you’re warmer because some of that energy has turned into thermal energy, heating up your muscles.
This is a great example of how energy changes form in real life! The total energy of the skateboard, you, and the surrounding air can be described as internal energy—it includes all the energy of the particles making up the skateboard, your body, and the air as they interact and move. So, even when the skateboard stops, the energy doesn’t disappear—it just changes form!
Is heat and temperature the same?
Is heat and temperature the same?
No, heat and temperature are not the same, though they are closely related!
Temperature is the measurement of the average kinetic energy of particles' motion. Faster movement of the particles means greater average energy of motion and higher temperature. On the other hand, heat is the transfer of internal energy from a warmer object to a cooler one due to temperature differences. Thermal equilibrium is a point or condition in which there is no internal energy transfer happening.
Imagine you leave a cup of ice water outside on a hot day. The ice starts to melt, and the water gets warmer. Now, think about this: Where does the heat come from to melt the ice, and why does the temperature of the water increase as the ice melts?
This question invites you to think about how energy moves and changes form in everyday situations, and helps you connect heat, temperature, and the behavior of matter—key ideas in science! What do you think happens to the particles in the ice and water? How do these changes relate to energy?
When you leave a cup of ice water outside on a hot day, the heat comes from the surrounding air, which is warmer than the ice water. Heat flows from the warm air to the cold ice, causing the ice to melt.
As the ice melts, the heat energy causes the water molecules in the ice to move faster and spread apart, changing the solid ice into liquid water. The temperature of the water increases because the particles in the water are moving more quickly as they gain energy from the heat.
So, the key idea is that heat flows from the warmer air to the cooler ice, and this heat energy causes the temperature of the water to rise as it melts. The particles in the ice and water are gaining energy and moving faster, which is why the water becomes warmer over time.
Modes of Heat Transfer
Modes of Heat Transfer
Conduction
Conduction
Conduction is the transfer of heat through direct contact between particles in a material, typically solids.
Example: As you can see above when a metal rod is heated in a fire, the heat from the fire transfers to the metal through direct contact. The particles at the heated end of the rod move faster and pass their energy to the nearby particles. This process continues along the rod, spreading the heat from the hot end to the cooler end.
Convection
Convection
Convection involves the transfer of heat through the movement of fluids (liquids or gases).
Example: When a cooking pot is heated over a fire, the heat from the flame warms the pot. As the pot gets hotter, it heats the air inside it. The warm air becomes less dense and rises, while cooler air moves in to take its place. This creates a cycle of air movement called convection. The heat is transferred from the pot to the air, causing the air to circulate inside the pot. This process helps cook the food more evenly and that's hoe pressure cooker works.
Radiation
Radiation
Radiation is the transfer of heat through electromagnetic waves, requiring no medium.
Example: An example of radiation is the heat you feel from the sun. The sun emits energy in the form of electromagnetic waves, which travel through the vacuum of space. This energy doesn’t need a medium (like air or water) to travel through, unlike conduction or convection. When these rays reach Earth, they transfer energy to your skin, making you feel warm. This process is known as radiation, where heat is transferred through electromagnetic waves.
Conduction, Convection, and Radiation
Conduction, Convection, and Radiation
The three modes of heat transfer (conduction, convection, and radiation) often interact in everyday cooking. Here's a comprehensive example of using a metal pot on a gas stove to boil water:
1. Radiation:
The gas stove produces a flame, which emits thermal radiation.
This radiant energy travels through the air and is absorbed by the base of the metal pot.
2. Conduction:
Once the base of the pot is heated, conduction takes over.
The heat is transferred through the metal (a good conductor) from the base to the sides and upper parts of the pot.
Simultaneously, the heat conducts from the inner surface of the pot to the water in contact with it.
3. Convection:
As the water at the bottom of the pot gets heated, it becomes less dense and rises.
Cooler, denser water from above moves down to replace it.
This creates convection currents in the water, which distribute the heat evenly throughout the liquid.
Interaction in Action:
The gas flame (radiation) heats the pot.
The pot (conduction) transfers heat to the water at the bottom.
The heated water circulates (convection) and ensures all parts of the liquid eventually reach the boiling point.
This synergy ensures efficient heating and cooking, leveraging all three modes of heat transfer to perform a single task.
Think about this: On a cold day, you stand near a campfire and feel warm, even though you’re not touching the fire or the heated objects around it. How do you think the heat from the fire is reaching you, and which mode of heat transfer is responsible for this warmth?
This question encourages you to think about how heat can move (by conduction, convection, and radiation) and how each method works in real-life situations. How can you explain the warmth from the fire using these three modes of heat transfer?
The warmth you feel near the campfire is due to radiation. The fire emits energy in the form of infrared radiation, which travels through the air without needing any contact. When this radiation reaches your skin, it transfers heat to you, making you feel warm, even though you’re not touching the fire.
So, in this case, radiation is the main mode of heat transfer responsible for the warmth you feel. There’s no need for the air to touch the fire or your skin directly, just the energy being emitted from the flames and absorbed by your body.
Other Types of Energy
Other Types of Energy
There are many more types of energy aside from thermal energy. The following are some of those:
Chemical Energy: Energy stored in chemical bonds, released during chemical reactions like combustion or metabolism.
Electrical Energy: Energy associated with the movement or presence of electric charges, used in powering circuits and devices.
Nuclear Energy: Energy stored in the nucleus of atoms, released through fission, fusion, or radioactive decay.
Radiant Energy: Energy carried by electromagnetic waves, such as light, radio waves, or X-rays.
Mechanical Energy: The sum of kinetic and potential energy in a system, enabling work to be done.
Sound Energy: Energy carried by vibrations through a medium, such as air or water, perceived as sound.
Magnetic Energy: Energy associated with magnetic fields, often used in motors or generators.
Other References
Other References
Let's Have a Game!
Let's Have a Game!
Checking for Conceptual Understanding
Checking for Conceptual Understanding
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