Work

Learning Objectives: Define: applied force, work, energy, positive work, negative work. Distinguish between positive and negative work. Recognize situations where no work is performed on an object. Determine the component of an applied force that acts in the same direction as the displacement. Express the correct SI fundamental or derived unit for work and energy. Recognize that work is a scalar quantity. Calculate work graphically from an applied force versus displacement graph. Give examples how energy is transferred from one object to another. Recognize that when energy transformations take place not all energy is used to produce useful work. Solve problems involving work and energy.

Key Concepts: In this unit students will increase their abilities to: Work is the product of an applied force and the displacement in the direction of the applied force. Only the component of the applied force acting in the direction of the displacement contributes to the work done. 1 J = 1 Nm is the unit for work. Work is a scalar quantity. Work will be positive when the applied force and the displacement are in the same direction. Work will be negative when the applied force and the displacement are in opposite directions. Work can be determined graphically by finding the area under an applied force versus displacement graph. Energy is the ability to do work. since not all of the energy goes into doing useful work. Some is converted into heat or other types of energy. Maximizing efficiency during energy transformation helps to conserve valuable resources.