Work, energy and power
Connect force and displacement to changes in motion, follow a spring’s stored energy, and distinguish an energy transfer from its rate.
Key knowledge
For a constant-mass Newtonian particle, work by the net force along its displacement equals the change in kinetic energy K = ½mv².
Values and equations
W_net = ∫ F_net · dr = K_f − K_i; K = ½mv²
- W_net
- Net work along the trajectory J
- F_net
- Net vector force N
- r
- Position vector m
- K
- Particle kinetic energy J
- m
- Particle mass kg
- v
- Particle speed m s⁻¹
Conditions and scope
- Use an inertial frame, constant mass and classical particle mechanics.
- Net work includes every force on the particle; v denotes speed in the kinetic-energy expression.
Sources · 5
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
- Physics, Part I (Class XI; reprint 2026–27)National Council of Educational Research and Training (NCERT)Textbook chapter · PDFChapter Five: Work, Energy and Power
- Classical Mechanics: MIT 8.01 Course Notes (2022 notes)Peter Dourmashkin — Massachusetts Institute of Technology, MIT OpenCourseWareCourse notes · PDFChapter 13: Energy, Kinetic Energy, and Work
Siyavula2 sources
- Physical Sciences, Grade 12 (online text)SiyavulaTextbook chapter5.2 Work
- Work–energy theorem · Physical Sciences 12SiyavulaTextbook chapter
- University Physics, volume 1: Work-Energy TheoremSamuel J. Ling, Jeff Sanny and William Moebs / OpenStax, Rice UniversityTextbook chapter
Evidence and review
OpenStax 7.3, derivation and equations 7.8–7.9.
2026-10-10 · Particle work-energy theorem only; an extended body's internal energy and relativistic kinetic energy are not covered.
Foundational review
2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.
Sources from other places
Scope or convention differs
Classical net work equals the change in translational kinetic energy.
The theorem and braking example agree; this teaching section does not derive the full variable-force vector path integral.
Siyavula
- Work–energy theorem · Physical Sciences 12 South AfricaEnglish
5.3 Work–energy theorem; Worked example7
- Work–energy theorem · Physical Sciences 12
Related articles
Work, kinetic energy, potential energy, and power ↗Entry details
Permanent link to this entry ↗- Record identity
- work-energy
- Revision
- reference-core.1
- Published lesson seed
- work-kinetic-potential-energy-power