energy - ability to do work or transfer heat  

• force - any type of push/pull placed on an object
• work - energy used to make an object move against a force
  • work = force x distance
• heat - energy transferred from hotter object to colder one
• kinetic energy - energy of motion
  • Ek = 1/2 mv2
  • thermal energy - from kinetic energy of molecules in a substance
• potential energy - energy based on relative position
  • Ep = mhg, where g = 9.8 m/s2 (gravitational constant)
  • chemical energy - from potential energy in bonds
• electrostatic energy - interactions w/ charged particles; form of potential energy
  • Eel = (kQ1Q2) / d
  • positive when 2 charges repel each other, negative when attracting each other
• joule - SI unit for energy
• calorie - amount of energy required to raise temperature of 1g of water by 1°
  • 1 calorie = 4.184 joules
  • 1 Cal = 1 nutritional calorie = 1000 calories = 1 kcal

internal energy - sum of all kinetic/potential energy in a system  

• 1st law of thermodynamics - energy is conserved, moves between system/surroundings
• numerical value of E can't be found, only change in E (DE)
• DE = Efinal - Einitial
• DE negative when energy lost (exothermic)
• DE positive when energy gained (endothermic)
• DE = q + w
  • q positive when heat moves from surroundings into system, negative when heat moves from system into surroundings
  • w positive when surroundings work on system, negative when system works on surroundings

system - area isolated for study  

• surroundings - everything other than the system in question
• closed system - can exchange energy but not matter w/ surroundings

state function - property of system determined by its condition/state  

• doesn't depend on how a change is carried out
• examples of state functions - E, DE
• not examples of state functions - work, heat