HEAT ENERGY
Heat- Form of energy that makes atoms and molecules vibrate. As heat energy is added to something, (ex: water) molecules vibrate and water becomes hot,
boil --- steam. As more heat is added molecules try to move farther apart.
Calorie- Unit of heat measurement. 1 calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.
Kilocalorie=1000 calories. A unit of 1000 calories used in measuring food energy.
Molecular Motion- Movement of molecules within a form of matter. Solid, liquid, gas.
Temperature Scales-
Fahrenheit- named after German scientist, Gabriel Fahrenheit, 1714.
H2O freezes at 32
H2O boils at 212
Celsius- Named after Swedish scientist, Anders Celsius, 1742.
H2O freezes at 0
H2O boils at 100
Types of Heat Transfer
Conduction- As molecules bump into each other they transfer heat. Example: Holding a hot cup of cocoa. Fingers get hot because molecules are touching sides of cup which is hot.
Convection- Heat transfer from or to something that can flow, like water or air. Example. When you blow a spoonful of hot soup. Air molecules pick up heat from the soup by conduction and heat flows away.
Radiation- Heat traveling as infrared energy. Infrared is energy that you feel from the sun or a light bulb.
Microwaves- Electromagnetic waves that greatly affect polar molecules, such as water. Heats food using the principle of friction.
Advantage-cooks food fast.
Disadvantage-uneven cooking.
Energy and Body Weight
Weight gain is healthy and important for growth and development.
Birth---->Adulthood. As one gets older, energy intake should decrease.
Converting Temperature Values
Fahrenheit --- Celsius
C=5/9(F-32)
1. subtract 32
2. multiply by 5
3. divide by 9
Celsius --- Fahrenheit
F=9/5C+32
1. multiply by 9
2. divide by 5
3. add 32