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Heat energy
- 2. At your agemost likely you have already experienced playing under the sun for several hours. After even just a couple of hours, you probably already felt your sweat running down you back or rolling off your face. You may have felt thirsty and started thinking of cold drinks or even ice cream. And you may have felt that your skin was not only reddish but also sticky. Worse, you may have started to smell a little too musky. You must have felt all these because of the heat energy that you received from the sun.
- 3. SOURCES OF HEATENERGY – form of energy that is produced from the movement of the molecules in a solid, liquid, or gas. The sun is the main source of heat energy on Earth. This form is called solar energy. Heat also be obtained from sources such as Earth itself, burning fuel, and electricity.
- 4. - Earth asthe source of heat energy. near the surface of the Earth are hot water and rocks that are trapped to generate heat energy for homes and other buildings. Greater amount of heat energy are sourced from the Earth’s mantle, which is composed of molten lava – or extremely hot rocks. These rocks are thrown off onto the surface of Earth during volcanic eruptions. In countries with many volcanoes such as Iceland, Italy, New Zealand, and the United States, heat energy from geothermal sources are used to produce electricity.
- 5. - any flammablesubstance that produces heat when it is burned. Among of those: charcoal, gasoline, kerosene, oil, and wood. Burning charcoal – needed to grill some of the food during picnics. Gasoline – converted into heat energy that causes vehicle to move. Kerosene, oil, and wood – also a source of heat energy they are utilized in the right manner.
- 6. - kind ofenergy that can build up in one place or flow from one object to another as it is carried by moving electrons through a wire. - considered an artificial source of heat energy unlike the sun, geothermal sources, and fuels which are deemed natural sources. Flow of electricity can be a source of heat energy for some appliances such as light bulbs, electric lamps, stoves, flatirons, toasters, and heaters.
- 7. EFFECTS OF HEATENERGY ON MATTER • Heat energy – measured in terms of temperature. • Temperature – hotness or coldness of matter. • Matter with very active molecules has high temperature and is said to be hot while matter with molecules that move around less has low temperature and is referred to as cold.
- 8. A. CHANGES INPHASE OF MATTER change from one phase to another. Ex: Bar of butter will melt when it is placed in a pan heated over a fire Ice cubes will turn into liquid when taken out of cold Those changes are called melting. It is a change from solid to liquid phase.
- 9. A. CHANGES INPHASE OF MATTER Heat can cause changes from liquid to gas phase, and it is called evaporation. Ex: Boling water in a kettle, amount of water decreases after some time because part of it has turned into water vapor. When water vapor cools, it releases heat and turns back into liquid. The change in phase from water vapor to liquid is called condensation.
- 10. B. CHANGES INVOLUME OF MATTER Objects get bigger when they get hotter and get smaller when they cool down. Through expansion, solid increase in size or volume when heat is applied to them. Ex: siopao will expand when exposed to heat and will contract when cooled. Balloon inflated when heated
- 11. B. CHANGES INVOLUME OF MATTER Liquid also expand when heated. We often found spilling out of a kettle when the water boils. Heat increases the energy of the water molecules and makes them move faster. In turns, the movement of the molecules causes them to occupy wider space. When heat is released, the water in the kettle settles.
- 12. FORMS OF HEATENERGY TRANSFER
- 13. - form ofheat energy transfer. Heat causes molecules to moves faster and collide with molecules near it, transferring the heat from molecule to molecule. - Materials that conduct heat are called conductors. - Ex: - Metals like aluminum, iron, steel, and copper
- 14. - Insulators –materials that does not transmit, conduct, or allow heat to pass through. - Ex: - Plastic (handles of most frying pans - Rubber - Wood
- 15. - the movementcaused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat. - Ex: - When boiling water in a pan, the heated water molecules near the bottom of the pan expand and become less dense.
- 16. - energy travelsin space through waves, heat is transferred from the source to the receiver in a form of heat transfer. - Ex: - Bringing a hand near a lighted candle or bulb without touching it, you will find out, although it is inches away from the flame, the hand will fell the heat from the candle or bulb. This is because the heat from the lighted source has radiated to the hand.
- 17. - Ex: - Sun’srays radiate to plants provide them with the sunlight they need for photosynthesis. The sun is millions of kilometers away but its intense heat radiates to Earth and is utilized by the different living things on the planet.
- 18. PROTECTION FROM EXCESSIVEHEAT Extreme heat can be dangerous for all people, especially for children like you. It may lead to different conditions such as fainting, heat stroke, muscle cramps, and prickly heat. 1. Avoid too much exposure to the sun’s heat, especially from ten o’clock in the morning to two o’clock in the afternoon when the sun’s rays are at their harshest. If you have to stay outdoors under the sun, wear sunblock or sunscreen on you skin. You may also put on a wide-brimmed hat or use an umbrella to protect yourself from the sun’s rays. 2. Drink eight to ten glasses of water and other liquids daily to keep from being dehydrated. Dehydration is the condition when the body loses much of its fluids and salts. This is dangerous to the human body; when the body loses a significant amount of fluids and salts, these are not quickly replaced. Too much loss of water and salts in the body can cause death.
- 19. PROTECTION FROM EXCESSIVEHEAT 3. Choose the right kind of clothing. In the Philippines, it is best to wear loose-fitting clothes that are made of cotton fabric. This kind of textile easily absorbs heat and allows air to pass through its fibers, thus cooling the body. 4. Stay alert for signs and symptoms of illnesses due to extreme heat such as dizziness or fainting, nausea, headache, rapid breathing, and extreme thirst. If you feel any of these signs, move to a cooler place and drink lots of water and other liquids to replenish the lost salts and prevent dehydration. 5. Never play with any source of light or heat energy. Use heated appliances such as stoves and flatirons with much caution and under adult supervision. Follow correct procedures when handling them. For instance, when working with kitchen appliances, never stay too close to sources of fire and heat. Handle hot spots and pans with pot holders and never with your bare hands, as the heat from these items will transfer to your hands and burn them.