What is deriving: Definition and 1000 Discussions

SI derived units are units of measurement derived from the
seven base units specified by the International System of Units (SI). They can be expressed as a product (or ratio) of one or more of the base units, possibly scaled by an appropriate power of exponentiation (see: Buckingham π theorem). Some are dimensionless, as when the units cancel out in ratios of like quantities.
The SI has special names for 22 of these derived units (for example, hertz, the SI unit of measurement of frequency), but the rest merely reflect their derivation: for example, the square metre (m2), the SI derived unit of area; and the kilogram per cubic metre (kg/m3 or kg⋅m−3), the SI derived unit of density.
The names of SI derived units, when written in full, are always in lowercase. However, the symbols for units named after persons are written with an uppercase initial letter. For example, the symbol for hertz is "Hz", while the symbol for metre is "m".

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  1. ChristineMarie

    Molar Free Energy of an Ideal Gas at Temperature T and Pressure P

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  2. bearcharge

    Deriving Tanabe Sugano diagram

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  3. J

    Need help with deriving air drag equation

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  4. H

    Deriving Boltzmann's Distribution

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  5. K

    Projectile Motion: Deriving 2g^2

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  6. P

    Deriving the Combined Gas Law

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  7. T

    Deriving formula for MA of differential windlass

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  8. PsychonautQQ

    Deriving projectile motion result

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  9. C

    Deriving spherical unit vectors in terms of cartesian unit vectors

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  10. C

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  11. R

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  12. 2

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  13. E

    On deriving response function in simple low pass filter

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  14. fisher garry

    Schrødinger equation deriving diff equation

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  15. binbagsss

    Deriving ##\nabla_a w_b## Using Leibniz Rule & Definition

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  16. P

    Deriving Angular velocity from Euler's?

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  17. J

    Deriving the electron speed from a specified orbital

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  18. P

    Deriving Metric $$g_{ij}$$ w/ Respect to Time t

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  19. 2

    Deriving the ground state energy of a hydrogen atom?

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  20. P

    Deriving a Bound for a System of Coupled PDEs Using the Energy Method

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  21. M

    Deriving gravitational potential energy (by bringing mass from infinity to r)

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  22. S

    How to Derive the Equality Involving u^s(p) and Spin 4-Vector?

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  23. J

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  24. michael879

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  25. C

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  26. F

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  27. Y

    Help deriving an equation using chain rule

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  28. F

    Deriving Equation Relating Angle of Incidence to the Angle of Refracti

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  29. F

    Deriving the time dilation? equation of Lorentz transformation

    Homework Statement It is not an official question but a request for pointers. I am trying to derive the Lorentz time equation to understand the intuition behind it. My math skills are not very good so it might be an obvious question for you. Please see below for my attempt. The variables are...
  30. deedsy

    Deriving sin(a-b) trig identity using Cross Product of Unit Vectors

    Homework Statement A and B are two unit vectors in the x-y plane. A = <cos(a), sin(a)> B = <cos(b), sin(b)> I need to derive the trig identity: sin(a-b) = sin(a) cos(b) - sin(b) cos (a) I'm told to do it using the properties of the cross product A x B Homework Equations A x B =...
  31. 2

    Deriving the formula for electric potential?

    Homework Statement I'm getting really confused when it comes to electric potential. The definition I am using is 'the work done per unit charge on a small positive test charge when it is moved from infinity away to a point'. My first problem is that I'm not sure whether 'the work done' refers...
  32. gimak

    Deriving work-kinetic energy theorem for rotational motion

    Homework Statement How to derive W=(.5*I)*((ωf^2)-(ωi^2)) from W=τ*(θ) Homework Equations The two equations seen above (big W is work; little w is rotational velocity, τ is torque, alpha=rotational acceleration). s=r*θ a=r*(alpha) (ωf^2)-(ωo^2)=2*(alpha)*(θ) F=r*τ F=ma...
  33. D

    Deriving Lorentz contraction from Michelson-Morley experiment

    In order for the light to take the same amount of time for both paths in the interferometer, simple geometry implies that the ratio between length and width will have to decrease. A straightforward derivation gives L/W=Sqrt(1-v^2/c^2) where the velocity v is in the direction of the length...
  34. L

    Deriving Orbital Motion from Collisions in Travel along Chords

    Homework Statement Inscribe N chords of equal length within a circle of radius r. A body of mass m travels at constant speed v along the chords and is perfectly reflected in each collision with the circle (there is no momentum change tangent to the circle). Show that the radial momentum change...
  35. E

    Deriving a volume formula, answer seems to be correct but is negative.

    I'm an engineering student, and I'm making a formula for the volume of liquid in a cylinder that is cut in half diagonally. r is the radius, h is the height from the bottom to the top of the sloped flat bottom, and L is the height of the water within the cylinder. So when L = h you would expect...
  36. T

    Deriving the Lorentz Transformation

    Hello everyone. I am attempting to teach myself about special relativity, and have learned a derivation for the Lorentz transformation. Before I go any farther I want to clear up the parts I don't understand right now and check that I am correct about the parts I do understand. Here I will...
  37. J

    Question about deriving TE Schrodinger WE

    To start, we have: ψ=e^{i(kx+wt)} ψ_x=ikψ ψ_{xx}=-k^2ψ λ=\frac{h}{p} k=\frac{2π}{λ} E=\frac{p^2}{2m}+V Then, multiply both sides of energy equation by ψ to get: Eψ=\frac{p^2}{2m}ψ+Vψ And replace -k^2 in the wave equation with -\frac{p^2}{hbar^2}. Then plug into energy equation for p^2 to get...
  38. Solibelus

    Deriving the displacement of an object

    Hi, I'm trying to derive the displacement of an object with proper acceleration (constant) α. t is our laboratory time. The goal: x(t) = {1 \over α} [ \sqrt{1+α^2t^2} -1 ] How to approach this? :( Note for anyone who's wondering: no, this is not homework...
  39. S

    Manipulating Tensor Expressions to Derive the Poincare Algebra

    Hey guys, as this is a basic QFT question, I wasn't sure to put it in the relativity or quantum section. Since this question specifically is about manipulating tensor expressions, i figured here would be appropriate. My question is about equating coefficients in tensor expressions...
  40. S

    MHB How do I derive and solve the equation for the athlete's running speed?

    I'm having problems getting going on the following question, any help appreciated: As part of his training an athlete usually runs 80 km at a steady speed of \(v\) km h. One day he decided to reduce his speed by 2.5 km h and his run takes him an extra 2h 40 mins. Derive the equation...
  41. M

    Deriving electrical potential

    Hi. I have no idea how to do this. It's complicated because the length here is a variable. I posted the same question before but there was a little mistake so I am reposting this again. The picture below shows the potential due to ring charge. Please show the full steps of deriving the...
  42. A

    MHB Deriving potential energy by simulation method

    The picture shows the potential due to ring charge. Please show the full steps of deriving the equation of electrical potential. I don't know how to start at all. NOTE: The electric potential of the revolving symmetrical ring electric charge related to the axis z as depicted in the diagram...
  43. S

    MHB How Can I Correctly Derive the Quadratic Equation from a Train Speed Problem?

    I'm having difficulty deriving a quadratic from the info in this question: A train usually covers a journey of 240 km at a steady speed of \(v \text{ kmh}^{-1}\). One day, due to adverse weather conditions, it reduces its speed by 40 \text{kmh}^{-1}\) and the journey takes an hour longer...
  44. 2

    Deriving the formula for the change in entropy

    Hello. I was reading Hyperphysics website and could not get one particular part. I am providing a picture of the equation I am having trouble with: http://i.snag.gy/W3CC3.jpg The particular part that puzzles me is the relation around the third equation sign. From the formula there one can think...
  45. A

    Deriving motion of a displaced piston on a gas cylinder

    First, I'm a second year high school physics student so my thinking may be half-baked. I was wondering what motion a piston would exhibit if it was the frictionless lid of an ideal gas cylinder with a constant amount of air, and if it was pushed or pulled a little bit. There would be a...
  46. F

    MHB Interpreting Constant A & Deriving k in Air Pressure Decay

    hey guys! I'm really confused as to what this question is trying to ask me! can someone help me out :) Air pressure decays approximately exponentially at about 0.4 per cent for each rise of 30 metres above sea level. If we let p = p(h) denote air pressure (measured in some appropriate units) at...
  47. Q

    Deriving Coulomb's law and other fundamental equations from F=ma?

    I saw a joke crib sheet for a physics class that said "F=ma, derive the rest," but is it actually possible to derive at least electricity and magnetism questions from Newton's second law?
  48. rpthomps

    How Is Linear Velocity AE Derived in a Scholarly Paper?

    Good afternoon, I am making way through this paper and I am having trouble "seeing" how the linear velocity AE is derived at the top of...
  49. S

    Deriving wave equation from Lagrangian density

    Hi, This is a worked example in the text I'm independently studying. I hope this isn't too much to ask, but I am stupidly having trouble understanding how one step leads to the other, so was hoping someone could give me a little more of an in-depth idea of the derivation. Thanks. Homework...
  50. J

    Deriving Covariance between S and N: E(SN) - ìXìN

    consider the following model for aggregate claim amounts S: S=X1+X2+...+XN where the Xi are independent, identically distributed random variables representing individual claim amounts and N is a random variable,independent of the Xi and representing the number of claims.let X has ìx and...
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