Work and the work-energy theorem
Variant i Dynamics first
This tutorial helps students relate force and displacement to work and to associate the net work done on an object to the change in kinetic energy of the object.
Topics Mechanics / Energy: systems, energy, energy conservation, and forces
Materials
Materials by the UW team
- Instructor Guide
- Pretest
- Exam Questions
- Equipment List
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Tutorial details
Students begin by considering a block that moves across a frictionless, horizontal table while a hand pushes on the block doing positive work. First they determine the relative directions of the force by the hand and the displacement and describe the motion of the block. Students then repeat the exercise for the case that the work by the hand is negative. The idea of work as a scalar product is also introduced. Similarly, the idea of net work is developed by considering motion with two forces acting on the block. At the end of the first section, students relate the motion of the block to the net work done on it and are led to recognize that their results are consistent with the work-energy theorem.
In the second part of the tutorial students apply the work-energy theorem in several cases involving one or more forces acting on various objects. The final case they consider that of a simple harmonic oscillator (a block connected to a spring).
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Prerequisites
Students should have previously studied work and kinetic energy.
Coming Soon! We hope to release the discussion section on each tutorial soon.
