Student difficulties with the concept of work in introductory physics

In order to apply the principle of energy conservation correctly, students need to be able to calculate the work done on a deformable system. The distinction between calculating work on a non-deformable system and on a deformable system is one that is only rarely made in introductory texts and lectures. At the University of Washington, the Physics Education Group has been developing research-based tutorials to supplement traditional instruction in textbooks, lectures, and labs. We will discuss how students frequently misapply the definitions of work that they are taught for non-deformable systems and ways in which this affects instruction on energy conservation. Results from student pretests, post-tests, and individual demonstration interviews will be presented.