Introduction to Energy AP Environmental Science

What is Energy? Energy is a measurable quantity that can be stored in a physical system. Energy can be transferred from one system to another and so cause changes.   When energy is transferred from one system to another, we refer to the energy being transferred as either heat or work.

Forms of stored energy – chemical, elastic, nuclear, gravitational Forms of Energy Forms of moving energy – kinetic, thermal, electrical, radiant (light), sound Forms of stored energy – chemical, elastic, nuclear, gravitational

Laws of Thermodynamics First law of thermodynamics – energy can neither be created nor destroyed   Second law of thermodynamics can be stated in three different ways: 1. Order tends to move toward disorder 2. No heat engine is ever 100% efficient 3. High quality energy degrades to low quality energy during energy transformations or transfers

Laws of Thermodynamics In any process, no energy is ever lost (it is always conserved). Rather, energy becomes less useful – it can do less useful work. As time goes on, energy is degraded. It goes from more useful forms (such as mechanical or chemical potential) eventually to the least useful form, thermal energy.

Power vs. Energy Energy – the ability to do work or cause change (measured in Joules) Power – the amount of work done or energy transferred/transformed per time (measured in Watts)  Power is a rate! The rate at which energy is used or consumed.

Equation: Power= Energy/Time Power vs. Energy Equation: Power= Energy/Time Unit: J/s or Watts Example: A lightbulb uses 3600 J of energy in 30 seconds. What is the power of this?