Nov 25, 2007 · The discussion centers on finding the derivative of the volume of a cone, represented by the formula V = (1/3)πr²h. Participants clarify that to compute the derivative, one must identify the …

Oct 13, 2025 · Browse this month's most popular physics articles, guides, tutorials and FAQs from the community expert authored Physics Forums Insights Blog.

Aug 29, 2025 · In Dirac's Principles of Quantum Mechanics published in 1930 he introduced a "convenient notation" he referred to as a "delta function" which he treated as a continuum analog to …

Jan 12, 2026 · Hi All While going through my book on QFT for mathematicians (What Is a Quantum Field Theory? by Michel Talagrand) I came across the following: 'Quantum Mechanics, in its standard …

Mar 16, 2024 · Sometimes people use the word "universe" when they mean "observable universe." The observable universe is finite in volume because light has only had a finite time to travel since the Big …

Aug 27, 2011 · The discussion clarifies that 'k' in the equation 1/2mv² = kQq/r represents the Coulomb constant, valued at approximately 8.988 x 10^9 Nm²/C². It is defined as k = 1/4πε₀, where ε₀ is the …

Oct 9, 2015 · The wave number k = 2π/λ . But is defined as radians per unit distance. What is the correlation here between the wavelength and radians ?

Dec 23, 2015 · The discussion centers on the proof of the product rule for gradients involving the del operator (∇) and the dot product of vector fields A and B. It clarifies that while the dot product A·B …

Mar 7, 2012 · Join experts in discussing linear and abstract algebra topics. This includes vector spaces and linear transformations. Also groups and other algebraic structures along with Number Theory.

Jan 12, 2026 · I recently learned of a multiplication method of signed numbers using 2's complement. Here is the answer. What I want to know is how does this multiplication work? I understand that two's …