Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Section 1: Temperature and Heat • • Temperature A measure of the average kinetic energy of the particles in the object. As temperature increases, the average speed of the particles increases • SI unit: • Kelvin (K) • In science: • Celsius • To us: • Fahrenheit • Body temperature: • 37oC, 98.6oF Absolute zero Temperature at which molecular energy is at a minimum Particles NEVER completely stop moving Basis for: Kelvin Scale 1 K= 1oC on Celsius scale Only difference is how zero is determined Heat Transfer of energy between objects that are different temps. Always flows from higher temp lower temp SI unit: joules (J) Factors Affecting Heat How much heat an object absorbs or loses Mass of object Temperature change of object final temp- initial temp If there is not change, no heat flow Composition of object Section 2: Transferring thermal energy Convection Transfer energy in a fluid by the movement of warmer and cooler fluid from place to place. Fluids Liquids and gases • • Radiation Energy transfer by electromagnetic waves Different: • Doesn’t involved the movement of matter across space Conduction • • Transfer of energy by collisions between particles in matter that are in constant motion Conductors • Material through which energy can be transferred as heat • Example: metals Insulators A material in which heat flows slowly Examples: wood, fiberglass, air Determiners: How much energy is required to change the temp of the substance • • • Specific heat Heat required to raise the temperature of 1kg of material by 1K SI unit: J/(kg•K) Water: • 4,186 J/(kg•K) Specific heat cont’d Energy=specific heat x mass x temp. change Q=mc∆T Adding energy: Raises its temp or state of matter but not both at the same time Section 3: Using heat Thermodynamics First law of thermodynamics Total energy used in a process is conserved whether the energy transferred as a result of work, heat, or both Second law of thermodynamics Heat transferred as heat always moves from a higher temp. to a lower temp. Mechanical Processes Processes in which energy is transferred by work Example: Rubbing two sticks together to create fire Heat engines Chemical energy is converted to mechanical energy through process of combustion Two types Internal combustion 4 strokes: Intake, compression, power, exhaust External combustion