Table of Contents
Thermodynamics Gateway Page
In this module:
Kinetic and Potential Energy
The First Law of Thermodynamics
Systems and Sign Conventions
GOALS: When you have completed this module, you should be able to:
  • Give examples of kinetic and potential energy and their interconversions
  • State and give examples of the First Law of Thermodynamics
  • Define a system and point out where energy and work enter and leave it

What is energy? What is work? Energy and work are two terms it seems everyone knows but nobody can define. In chemistry, work is defined as movement opposed by a force. For example, when you lift a box into the air against the force of gravity, you are doing work. When you slide the same box across the floor against the force of friction, you are also doing work. When you blow up a balloon against the force exerted by the atmosphere, you are doing work. When you pull two magnets apart against the magnetic force holding them together, you are doing work.

Energy is defined as the capacity to do work. In each of the examples above, energy has to be spent to do the work. Thus, energy and work are really the same thing, just in a slightly different form. Energy is the cause and work is the result.

This module will introduce you to work and energy and show you how to set up problems relating objects and the energy and work they exchange with their surroundings.