Formula Definition and 1000 Threads

In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a chemical formula. The informal use of the term formula in science refers to the general construct of a relationship between given quantities.
The plural of formula can be either formulas (from the most common English plural noun form) or, under the influence of scientific Latin, formulae (from the original Latin).In mathematics, a formula generally refers to an identity which equates one mathematical expression to another, with the most important ones being mathematical theorems. Syntactically, a formula(often referred to as a well-formed formula) is an entity which is constructed using the symbols and formation rules of a given logical language. For example, determining the volume of a sphere requires a significant amount of integral calculus or its geometrical analogue, the method of exhaustion. However, having done this once in terms of some parameter (the radius for example), mathematicians have produced a formula to describe the volume of a sphere in terms of its radius:




V
=


4
3


π

r

3




{\displaystyle V={\frac {4}{3}}\pi r^{3}}
.Having obtained this result, the volume of any sphere can be computed as long as its radius is known. Here, notice that the volume V and the radius r are expressed as single letters instead of words or phrases. This convention, while less important in a relatively simple formula, means that mathematicians can more quickly manipulate formulas which are larger and more complex. Mathematical formulas are often algebraic, analytical or in closed form.In modern chemistry, a chemical formula is a way of expressing information about the proportions of atoms that constitute a particular chemical compound, using a single line of chemical element symbols, numbers, and sometimes other symbols, such as parentheses, brackets, and plus (+) and minus (−) signs. For example, H2O is the chemical formula for water, specifying that each molecule consists of two hydrogen (H) atoms and one oxygen (O) atom. Similarly, O−3 denotes an ozone molecule consisting of three oxygen atoms and a net negative charge.
In a general context, formulas are a manifestation of mathematical model to real world phenomena, and as such can be used to provide solution (or approximated solution) to real world problems, with some being more general than others. For example, the formula

F = mais an expression of Newton's second law, and is applicable to a wide range of physical situations. Other formulas, such as the use of the equation of a sine curve to model the movement of the tides in a bay, may be created to solve a particular problem. In all cases, however, formulas form the basis for calculations.
Expressions are distinct from formulas in that they cannot contain an equals sign (=). Expressions can be liken to phrases the same way formulas can be liken to grammatical sentences.

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  1. bknock

    Thin slits and accuracy of Kirchhoff's diffraction formula

    Imagine a single slit with plane light waves incident on it with a screen (ideally far enough from the slits to simplify the math). According to Kirchhoff's diffraction formula, when a very wide slit is doubled, average intensity (averaged over all diffraction angles) doubles, and so does E_peak...
  2. M

    Stray capacitance -- how to calculate formula....

    Hello, i am reading one book over the "tenichians radio receiver handbook", but there was a stray capacitance can somebody help me, how to calculate stray capacitance? of what arethe standard value of stray capacitance thanks. YES do you see the circuits the stray capacitance is 7pf and 320pf...
  3. M

    MHB Find Area Formula of Rectangle

    Let x denote the width of a rectangle with perimeter 30 feet. Find the area of this rectangle. Let me see. P = 2L + 2W 30 = 2L + 2x (30 - 2x) = 2L (30 - 2x)/2 = L A = LW A = [(30 - 2x)/2]x Correct? I guess we can simplify a little more. A = x(15 - x) Correct?
  4. F

    Distance formula vs similar triangles

    Hello, took a year off school, now shaking the rust off. so according to the book using similar triangles d=9.6 I understand how they got the answer, but i used distance formula from the point to the origin and got 9.8 I checked 9.6 and it checks out with the numbers but Idk why using the...
  5. J

    Solving Asymptotic Formula: Eq. 25 & 27

    In the following equation, $$P(x; a)= \frac{\gamma}{2\lambda L \eta} [\frac{1}{π^2N_F(a)\eta(1 - \frac{x}{a\eta})^2} + \frac{1}{π^2N_F(a)\eta(1 + \frac{x}{a\eta})^2} +\frac{2}{π^2N_F(a)\eta(1 - \frac{x^2}{a^2\eta^2})} [sin (\frac{π N_F(a)\eta(1 - \frac{x}{a\eta})^2}{2})sin (\frac{πN_F(a)\eta(1...
  6. H

    Find the formula for refraction angle?

    Homework Statement Homework Equations Snell's Law sin tetha1/v1 = sin tetha2/v2 n1 = c/v1 n1 . sin tetha 1 = n2 . sin tetha 2 The Attempt at a Solution I try to make triangle out of line PO, so that it will have correlation to tetha, since o = center, then let's say there's point C at...
  7. L

    I Havil's book "Gamma" page 57, formula

    Where does the 1 in the last line come from? Thank you!
  8. D

    Correct formula for deflection of a falling object

    Hello, I found a derivation on NASA and several others that say something different. Can someone tell me which is correct? They differ by a factor of 3. This is confusing because some places say an object falling from 100m should deflect by 3cm but NASA says .16mm. Those are more different...
  9. D

    I Formula for concentration of force (battle axe vs. a mace)

    I really hope someone can help. I have spent the last week several hours a day trying to get this answer via Google. I am doing research on the practical difference between a mace and axe in combat. Strangely enough there's almost nothing concerning the techniques of using a mace in period...
  10. Megan1000

    What is the formula to find inertia with velocity and mass?

    Homework Statement v=2m/s m=10kg find the inertia At first i did 2m/s times by 10kg which is 20 but i also did 2m/s divided by 10kg =0.2 and 10kg divided by 2m/s= 5 but I'm unsure which method is correct. and momentum apparently isn't the same as inertia... Inertia is when an object carries...
  11. M

    MHB Why Does tan(x + pi/2) Equal -cotx in Trigonometry?

    I decided to review a little trigonometry. Why does tan(x + pi/2) = -cotx? I cannot use the tangent of a sum formula because tan(pi/2) does not exist. How about tan(x + pi/2) = [sin(x + pi/2)]/[cos(x + pi/2)] and then apply the addition rules for sine and cosine?
  12. P

    Formula for bending a rod in the elastic range

    Is there a formula to calculate the radius that a rod of a given radius can be bent around while staying in the elastic range? For example, if I had a rod that was 1/4" in diameter and made of HDPE (which I think has a modulus of elasticity of 0.8 GPa), how would I calculate the minimum radius...
  13. P

    Formula for bending a rod in the elastic range

    Is there a formula to calculate the radius that a rod of a given radius can be bent around while staying in the elastic range? For example, if I had a rod that was 1/4" in diameter and made of HDPE (which I think has a modulus of elasticity of 0.8 GPa), how would I calculate the minimum radius...
  14. K

    I How Does the Hubble Parameter Relate to Galaxy Movement?

    This is the time derivative to calculate the speed which a galaxy moves away from another galaxy. I don't understand how they get from da/dt (xi − x1) to (∙a)/a a(t). (xi − x1). Could anyone explain this? vi(t) = d/dt (ri(t) − r1(t)) = d/dt a(t)(xi − x1) = da/dt (xi − x1)...
  15. S

    How do I put this series into a formula?

    Homework Statement Consider now a sample consisting of all possible n-digit integers where n is odd. Use your answers to the first two parts or otherwise to deduce a formula for the number of palindromic numbers within this sample.Your formula should be a function of n only. [6 marks] [Hint...
  16. binbagsss

    A Valence formula- fundamental domain- why truncation height?

    In the proof of the valence formula you integrate ##f'(t)/f(t)## around the boundary of the fundamental domain, with some modifications such as : - omitting the points ##i, \omega ## - since equivalence is allowed on the boundary, modifying as needed to ensure such points that are equivalent...
  17. K

    Rotational Inertia formula help

    A 24 kg solid door is 220 cm tall, 95 cm wide. What is the door's moment of inertia for rotation about a vertical axis inside the door, 17 cm from one edge? I've looked at examples of how to do this problem. They connect it to center mass but I get confused when determining what the center mass...
  18. S

    B Doppler effect formula confusion

    Hello! I am a bit confused by the Doppler effect. Based on the formula it seems that if the source moves towards me with speed ##v## I hear a frequency ##\nu_1## but if I move towards the source with the same speed ##v## I hear a different frequency ##\nu_2##. However according to the...
  19. David23454

    Solve equation using quadratic formula

    Homework Statement I'm having trouble with solving a certain form of an equation with the quadratic formula. I think I'm making a dumb mistake somewhere with my algebra, but I can't seem to find it. Solve with quadratic formula: 1/x^2=4/(0.02-x)^2 Homework Equations 1/x^2=4/(0.02-x)^2 The...
  20. mammou manel

    B How do I convert from lux to candela?

    hello i'm working on a project that consist on reading the light of LEDs on PCB to determine the color code (R,G,B) and light intensity but the sensor gives me values in LUX which is the illuminance and i need to convert them to Candela I found this formula in wikipedia but i didn't understand...
  21. moriheru

    A A "Proof Formula" for all maths or formal logic?

    I was wondering whether or not there could be a "master formula" . What I mean by a master formula is, maybe not even a formula, some mathematical expression that would allow mathematicians to prove statements simply by plugging in some numbers into a formula. So I guess in a way a I am...
  22. Z

    The Kirchhoff diffraction formula with small wavelength

    Homework Statement The fresnel-kirchhoff diffraction formula could explain diffraction,I think it should also produce the result with relatively small wavelength and large width slit in which case there is no diffraction. Homework Equations...
  23. binbagsss

    Modular Forms, Dimension, Valence Formula

    Homework Statement What is the dimension of ##M_{24}##? Homework Equations attached The Attempt at a Solution [/B] I am confused what the (mod 12) is referring to- is it referring to the ##[k/12]## where the square brackets denote an equivalent class and the ## k \equiv 2## / ##k \notequiv...
  24. I

    Derivation for number of periods finance formula

    Homework Statement Hi, I am reading this book called, Introduction to Corporate Finance, by Berk, Demarzo, Harford (second edition). In it they try to explain how to calculate the number of periods in a loan payment formula. Authors give the following equation. $$ 0 =PV + PMT \times...
  25. P

    B Not sure what this problem would be called....

    Hi, I am trying to write a function which would take two arguments: -> number of bits (which are a binary 0 or 1 value) N -> and acceptable number of mismatching bits M The function would statistically determine the probability of having M or less mismatching bits when randomly generating two N...
  26. J

    A What is the formula for calculating the Ascendant?

    I'm trying to figure out how to calculate the Ascendant for a programming application but I have little experience with this level of math. My formula is this: 1998 December 31st 13:15 Brussels, Belgium. double d2R = M_PI / 180; double R2d = 180 / M_PI; double latitude = 50.8503*d2R; double...
  27. D

    Drag formula used to calculate bullet hole depth?

    I'm writing a real time 3D physics simulator that simulate bullet ballistics. Can I use the air drag formula that factors in drag coeficient and outputs drag force to calculate how deep a bullet will penetrate a target material? Say I substitute air pressure with target material density. And...
  28. F

    Prerequisites to Cauchy Integral Formula

    Homework Statement Calculate the integrals of the following functions on the given paths. Why does the choice of path change/not change each of the results? (c) f(z) = exp(z) / z(z − 3) https://www.physicsforums.com/file:///page1image10808 i. a circle of radius 4 centred at 0. ii. a circle...
  29. K

    The significance of each term in Planck's Radiation Formula

    Homework Statement I(λ, T) is 4 pieces multiplied: (8π/λ4) (hc/λ) (1/(ehc/λkT-1) (c/4). 1. Identify the meaning of each term. 2. Which term(s) fix the ultraviolet catastrophe? The Attempt at a Solution Well I know that the energy of a photon is given by (hc/λ), and I'm fairly certain it was...
  30. terryds

    B Can Fringes Exist with Sine Value Greater Than 1 in Young's Double Slit Formula?

    In Young's double slit formula, the equation is d sin \theta = m \lambda Which means that sin \theta = m \lambda / d But, what if d < \lamda so the sine value becomes greater than 1? Will there be any interference?
  31. G

    How to find Kepler's law from Newton's laws

    We were asked to do an experiment where we had to prove the equation: T2=(4π2m)/Mgr Where M is the mass of the mass stack in kg (0.3kg), m is the mass of the rubber bung in kg (0.0226kg), T is the time taken for one rotation in seconds, r is the horizontal radius of rotation in meters, and g is...
  32. U

    Derive formula using Conservation of Energy and Momentum

    Homework Statement Playing in the street, a child accidentally tosses a ball (mass m) with a speed of v=23 m/s toward the front of a car (mass M) that is moving directly toward him with a speed of V=20 m/s . Treat this collision as a 1-dimensional elastic collision. After the collision, the...
  33. K

    A Deriving the Kubo Formula for Viscosity in Thermal Relativistic QFT

    I am looking for a derivation of the following formula $$ \eta=\lim_{\omega\rightarrow0} \frac{1}{2\omega}\int dt dx\langle[T_{xy}(t,x),T_{xy}(0,0)]\rangle, $$ where $T_{xy}$ is a component of the stress-energy tensor. This is claimed in for instance https://arxiv.org/pdf/hep-th/0405231.pdf...
  34. Mr Davis 97

    Deriving the sum of sin and cos formula

    Homework Statement Show that ##a \sin x + b\cos x = c \sin (x + \theta)##, where ##c = \sqrt{a^2 + b^2}## and ## \displaystyle \theta = \arctan (\frac{b}{a})## Homework EquationsThe Attempt at a Solution We see that ##c \sin (x + \theta) = c \cos \theta (\sin x) + x \sin \theta (\cos x)##. So...
  35. B

    Integrating a Rhombus: Solving for Area Using the Change of Variables Formula

    Homework Statement Homework Equations N/A The Attempt at a Solution I solved part a. I got an answer of 140. For part b, however, I am stuck. I came up with a set of points for D in the xy plane [(0,3)(0,6)(4,5)(4,8)] giving me a rhombus. How do i integrate this? I tried to split up the...
  36. E

    Help in understanding sum of torque equation

    I've been reading my physics book and there they derived the formula ∑τ = Iα where τ is torque, I is moment of inertia of a rigid body and α is the angular acceleration. They did by taking an arbitrary particle on the rigid body with an applied external force tangent to the rotation. τ1 = Ftan *...
  37. S

    Calculate Max Lever Length for Toppling Block

    Moderator note: Thread moved from technical forum so formatting template is missing Hi, I have a block with a specified weight and a lever with a force at the other end. I was hoping someone could tell me what formula i need to work out the maximum length of lever before the block falls over.
  38. I

    Finding Formulas from Systematic Names: How Does the Number in Parentheses Help?

    Homework Statement Sodium chlorate(I) Sodium chlorate(V) Potassium nitride(III) Phosphorus(III) chloride Magnesium iodate(I) Homework Equations None The Attempt at a Solution I know the number in the bracket refers to what's before it, i.e. in sodium chlorate(V), the (V) means that the...
  39. S

    MHB Formula for Ellipse 'Change of Distance by Change of Theta'?

    I am working on planetary orbits in an ellipse where the sun is at the foci, not the centre of the ellipse. I need a formula that describes the 'Change of Distance by Change of Theta angle' where Distance represents the distance between a planet to the sun (Planet is on parameter, Sun is at...
  40. A

    MHB Not a "help need" but a question about "a self made square root formula"

    Hello,first time posting a thread not just here but generally so i'll try my best. So while i was in class we were learning about square roots,at first it seemed fairly easy,but when i asked my math teacher how do we find them more easily, he smiled and talled me:"The problem is,you just...
  41. Luca_Mantani

    A LSZ formula and Field Strength renormalization factor

    Hi all, I have doubts on the role of the Field Strength renormalization ##Z_\psi=1+\delta_\psi## when computing amplitudes. I never did this, maybe because it was not needed before, but i noticed that in the solution of a specific problem, to obtain the correct result, you need to multiply the...
  42. Elektrokaninen

    Formula for calculating the output voltage of a pickup coil

    It should be possible to calculate the output voltage in millivolts of a pickup coil at a given frequency, based on the number of turns of wire, the wire resistance / meter, the inductance of the coil in Henrys, coil capacitance, the BH max in Joule, or flux density in Tesla, and volume of the...
  43. F

    Newton interpolary difference formula

    Homework Statement I don't understand the meaning of the formula... For the circled part in the first photo , what is the meaning of f(x1 ,x2 ) ? and also f(x0 , x1 ) ? Homework EquationsThe Attempt at a Solution I used the highlighted formula to find the second divided difference . But ...
  44. J

    MHB Where does radius sin angle sin rotation come from?

    For calculating a new "x" point of rotation I found the formula: x' = radius * cos(angle + -rotation) which converts to: x' = radius cos angle cos rotation - radius sin angle sin rotation Where does "radius sin angle sin rotation" come from? Jerry D.
  45. Jack Mc

    Need Help Transposing the pressure drop formula

    Homework Statement Hi, Iv got to find the minimum diameter of a pipe if the pressure drops in a system is to be limited to 0.3bar. when delivered through a pipe of equivalent length 160m I have to use the formula Pressure Drop = 800lQ^2/Rd^5.31 I believe I have to transpose this to find...
  46. G

    Derivation of formula of normal acceleration

    Homework Statement 2. Homework Equations [/B] Consider a particle that is described by $$x(t)=(2.0-0.1t) \cos(0.5t)$$ and $$y(t)=(2.0-0.1t) \sin(0.5t)$$ t in seconds and x,y in meters. In previous subquestions we were asked to determine an expression for the module of the velocity vector and...
  47. Shaun Harlow

    A What is the formula 1/(dS/dE)>>0 and how does it apply?

    I am only aware that the formula has to do with entropy/thermodynamics. I could really use the help on how it applies in physics and what the formula is really about.
  48. B

    Semi-empirical mass formula: most stable isobar for odd A

    Homework Statement Using the Semi-empirical Mass Formula show that for fixed odd atomic mass number, A, the most stable isobar has a neutron to proton ratio given by N/Z = 1 + aCA2/3/(2aA) Homework Equations B(A,Z) = aV A − aS A2/3 − aCZ2A-1/3 − aA(Z − N)2/A + pairing term The Attempt at a...
  49. fisher garry

    Usage of Taylor's formula on stress analysis

    Moderator Note: Thread moved from forum Atomic, Solid State, Comp. Physic, so no homework template shown. What function do they use Taylor's formula on? And can you show how they derive it? I know how one derives Taylor formula. Thanks! The text i taken from this...
  50. C

    Dynamics question.... where did this formula come from?

    < Mentor Note -- thread moved to HH from the New Member Introduction forum, so no HH Template is shown > Hi there, I found a thread from 2004 that perfectly answered my homework question here, but I don't understand how the person who responded came up with the answer. I would have just...
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