Answer to Question #281511 in Physics for OMAR

Question

The relationship between kinetic energy of an object and the work done by the force(s) acting on it, called the work–kinetic energy theorem, is expressed formally as:

$\Delta$K ≡ K - K₀ = W

Why is this symbol ( ≡ ) used in the first part of the equation above? Why ( = ) is not used?

Please give full explanation about ≡ and why it is used here and in which situations it is used.

Answer 1

The reason why the equivalence sign is used instead of the equals sign is most likely that the writer decided to write this theorem in this way. Most online (Wikipedia, Khan Academy, OpenStax) and offline sources (An Introduction to Mechanics by Daniel Kleppner, ‎Robert J. Kolenkow, 2010, Introduction to Classical Mechanics: With Problems and Solutions by David Morin, 2008) use equals sign, not equivalence.

Email the author of your book or ask your professor why the decision to use this sign was made; there is zero difference between using ≡ and = in the work-energy theorem written this way.