HEAT TRANSFER VOCABULARY Heat: is energy of motion is kinetic energy Excited atoms Movement of atoms o Solids vibrate in place Jitter, wobble Atoms push apart = expand o Liquids & gases bounce & move around (linear) Hotter = faster motion, expand & push apart Heat transfer: Rule: heat always moves from hotter to colder Heat moves in 2 ways: 1. Radiation 2. Conduction Radiation: energy that is transmitted through space in rays, waves, or particles Source is the Sun Streams out in all directions Travels through space until it hits an atom Examples: 1. light 4. radio 2. X-rays 5. microwave 3. infrared 6. ultraviolet Reradiated Energy: energy that is radiated again Example: a. energy transfers from the Sun to the land or sea b. then from the land or sea back to the atmosphere Differential Heating: different materials heat up at different rates different materials can store different amounts of heat Example: o Water stores a lot of heat so it takes a long time to raise its temperature o Air stores only a little heat so it warms up quickly Conduction: the transfer of energy from one place to another by contact Heat/energy moves from molecule to molecule High energy molecule collides with a lower energy molecule and passes energy/heat to it o “hotter” molecule “cooler” molecule The first molecule loses energy; it gets cooler The second molecule gains energy; it gets hotter Example: o Metal spoon in a pot of soup Steel molecules in spoon receive energy by contact with hot water molecules Steel molecules “pass the message” or heat/energy along to their neighbors by conduction (contact) Handle of the spoon gets too hot to hold because energy/heat was conducted out to the end Heat transfers to your hand through contact Your brain tells you to let go of the hot spoon!
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