Stage 2: Energy

Stage 2: Energy

1. Temperature

   • Tempretature is porportional to the overage kinetic energy of particles in a substance or object
     • Adding thermal energy = heating
     • Removing thermal energy = cooling
       • Lowest possible kinetic energy on an object is -273.15 C or 0 K
     • Thermal equilibrium
       • Energy is constant, there no energy trasnfer
       • If two objects with different temperature are placed together, energy is transfered from the hot one to the cold one, after a whilem both will have the same temperature and they'll be in equilibrium
   • Can be measured in celsius, farenheit, or in kelvin
   • Thermal energy
     • The sum of kinetic and potential energy
   • Zeroth law of thermodynamics
     • All that matter is the temperature of each object

2. Energy Transfer

   • Energy must be added or removed from the object in order to change its temeprature adn cause it to expand or contract
     • Conduction
       • Conduction occurs as higher energy particles collide with and jostle neighboring lower energy particles, trasnfering kinetic energy from one particle to the next
     • Convection
       • Transfers energy through the physical movement of particles from one place to another
         • COnductors are good transfering energy, such as steel
         • Insulator are bad trasnfering energy such as wood
     • Added heat= expand Decrease heat= contracts
     • radiation
       • The transfer of thermal energy form electromagnetic waves, such as the sun or the microwave.
   • Thermal expansion
     • Is proportinoal to both: lenght (Li) and temperature change (T)

3. Heat capacity

   • Joule´s experiment established mechanical equivalence of heat 1 cal= 4.186 J
     • The calorie is the customary unit for measuring heat. One kilocalorie is the amount of heat added to raise the tmeeprature of 1 kg of water from 14.-15.5 Celsius
     • Heat is represented with "Q" and the SI units is Joules
     • 1C= 1kcal= 1000 cal
     • If +Q thermal energy is added
     • If -Q thermal energy was removed
   • Specific heat capacity
     • Is the thermal enrgy required to change the temeperature of a substance by 1 celsius
   • The calorimetry
     • The final temperature of the block and the water are equal, since the system i sin thermal equilibrimum
     • The total energy of the system is conserved

4. Phase changes and latent heat

   • boiling point
     • The part in the curve where the vapor pressure equals external pressure
   • equilibrium vapor pressure
     • pressure of a gas in equilibrium
   • evaporation
     • process of particles leaving the liquid phase and going into the gas phase
     • helps us cool when we excercise as we seat
   • Latent heat
     • Thermal energy required to change 1 kg of a substance from one phase to another
     • During the conversion process from one phase into another, the temperature of the system remains constant
     • Lf to freeze Lv to vaporize Ls to sublimate
     • Q=mLf

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