What is Derive: Definition and 620 Discussions

The dérive (French: [de.ʁiv], "drift") is a revolutionary strategy originally put forward in the "Theory of the Dérive" (1956) by Guy Debord, a member at the time of the Letterist International. Debord defines the dérive as "a mode of experimental behavior linked to the conditions of urban society: a technique of rapid passage through varied ambiances." It is an unplanned journey through a landscape, usually urban, in which participants drop their everyday relations and "let themselves be drawn by the attractions of the terrain and the encounters they find there". Though solo dérives are possible, Debord indicates that the most fruitful numerical arrangement consists of several small groups of two or three people who have reached the same level of awareness, since cross-checking these different groups' impressions makes it possible to arrive at more objective conclusions.The dérive's goals include studying the terrain of the city (psychogeography) and emotional disorientation, both of which lead to the potential creation of Situations.

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  1. Richie Smash

    Derive the equation of a line after x+(1/2)y =0 is mapped by T

    Homework Statement Hello hello, I am on the second to last question of 6 practice examinations I've been doing! ''There is a transformation matrix T = \begin{pmatrix} 4 & 9\\ 3& 4 \end{pmatrix} They want me to derive the equation of the line onto which the line x +(1/2)y = 0 is mapped by the...
  2. Richie Smash

    Derive an expression for the price of a pen in terms of p

    Homework Statement Hello there are two types of pens expensive and cheap. The ratio of the prices of the two is 3:7 The total cost for 30 of the cheaper pens and 10 of the expensive pens is $1568. I am asked to derive an expression for the cost of ONE of the expensive pens which i will...
  3. B

    Derive the relation between the P & R branches

    Hi, I have an assignment to derive the two following expressions: R(J)-P(J)=2B'(2J+1) R(J-1)-P(J+1)=2B''(2J+1) where Bis the rotational constant and prime ' stands for upper level and bis '' for lower level. Bv=Be-α(v+1/2) using the selection rules (I guess in this case ΔJ=±1) and...
  4. Alexanddros81

    Derive the expression for the work done by the friction force

    Homework Statement 14.6 The coefficient of kinetic friction between the slider and the rod is μ, and the free length of the spring is ##L_0 = b##. Derive the expression for the work done by the friction force on the slider as it moves from A to B. Neglect the weight of the slider. Homework...
  5. Alexanddros81

    Derive the expression for the work done by the ideal spring

    Homework Statement Derive the expression for the work done by the ideal spring on the slider when the slider moves from A to B. Assume that the free length of the spring is (a) ##L_0 = b##; and (b) ##L_0 = 0.75b## Homework EquationsThe Attempt at a Solution Can you check if my solution...
  6. P

    I Why can we WLOG derive Simpson's rule over interval -1 to 1

    On the Simpson's Rule wikipedia page they mention in their derivation that the calculation can be simplified if one notices that there is no loss in generality in setting ##a=-1## and ##b=1## for the integral ##\int_{a}^{b}P(x)\cdot dx## as a result of scaling. I'm not entirely sure what...
  7. B

    Derive a wave equation for an n mass coupled system

    1. Derive the wave equation for longitudinal vibrations in an extended 1-D system of masses and springs. The average distance between masses is D [m], the spring constants are K [kg/s2 ], and the masses are M [kg]. b) Determine the wave speed c as a function of D, K, and M. Verify that it has...
  8. Jenna

    Using Energy and momentum conservation to derive the equation

    Homework Statement I need to find the intial velocity of a ball, given the angle the pendulum bob swings through. I need to derive this equation. [/B] V0=4.43mtotalL1/2{1-cosΔθ}1/2/mball Homework EquationsThe Attempt at a Solution I have barely any attempts since I can't even think where to...
  9. J

    I How to derive number of nucleons in Universe?

    I understand that there are roughly ##N=10^{79}## nucleons in the visible Universe. This number comes from adding up the nucleons of ##100## billion stars in ##100## billion galaxies in the visible Universe i.e. $$N=\frac{10^{30}}{10^{-27}}. 10^{11}.10^{11}=10^{79}$$ where mass of sun is...
  10. D

    Derive Formula for Velocity of Object Approaching Earth

    Homework Statement A particle of mass m is dropped from a height h, which is not necessarily small compared with the radius of the earth. Show that if air resistance is neglected, the speed of the particle when it reaches the surface of the Earth is given by ##\sqrt {2gh}## ##\sqrt {\frac {R_E}...
  11. lfdahl

    MHB Derive a closed form and find its limit

    Let $S_n(k)$ be defined by: $S_n(k) = 1 + 2k+3k^2+...+(n+1)k^n$, where $|k| < 1$ and $n \in \Bbb{N}$. Derive a closed form for $S_n(k)$ and find the limit: $$\lim_{{n}\to{\infty}}S_n(k)$$.
  12. A

    Derive a general expression for range when launch angle=0

    1. The problem statement, all variables, and given/known data Homework Equations The Attempt at a Solution So basically I took vertical direction formula and I solved for "t". I then took the horizontal direction formula and solved for "x" or we can also call x the "Range" since that's...
  13. Gio83

    A Derive the Bianchi identities from a variational principle?

    Einstein's field equations (EFEs) describe the pointwise relation between the geometry of the spacetime and possible sources described by an energy-momentum tensor ##T^{ab}##. As well known, such equations can be derived from a variational principle applied to the following action: $$S=\int\...
  14. M

    Why is it necessary to derive the given velocity

    <Moderator's note: Moved from a technical forum and thus no template.> 1st time posting, be gentle. Physics with calc 1 Im reviewing my exam which i did poorly on and can't understand why things are done, i have many questions but ill start with one, and since I am new maybe someone can tell...
  15. J

    Derive trig equations 4, 5, and 6 from 1, 2, and 3

    Homework Statement Hi again, I will re-write this on behalf of a request. I am struggling trying to derive these equations for a physics lab. The equations asked to derive are the equations that describe a perfectly elastic collision between objects of identical mass. These are given to me...
  16. O

    Derive The Transfer Function from First Principles

    All, I need help deriving the Transfer Function of this circuit from first principles. http://i66.tinypic.com/24v3z9s.jpg
  17. L

    How to derive the slip angle for a trailer-car system?

    I just watched this video that perfectly explains how to derive the equations for the slip angle of a car: However, how could this be done for a three axle system (car-trailer)? Would you have to express distance a (in the video) in terms of b (distance from centre of gravity to the second...
  18. binbagsss

    Quantum Theory: derive EoM of action for a 'general' potential

    Homework Statement Action attached: To find the EoM of ##\phi ## / ##\phi^* ## Homework Equations The Attempt at a Solution [/B] Without deriving from first principles, using E-L equations I have: ## \partial_{u}\frac{\partial L}{\partial_u \phi} - \frac{\partial L}{\partial \phi} =0 ##...
  19. K

    Derive cos'x from cos(A)-cos(B)

    Homework Statement Use ##~\cos\alpha-\cos\beta~## to develop the formula for the derivative of cos(x) from the definition: $$\frac{d(\cos x)}{dx}=\lim\frac{\cos(x+\Delta x)-\cos x}{\Delta x}$$ Homework Equations $$\cos\alpha-\cos\beta=(-2)\sin\left( \frac{\alpha+\beta}{2} \right)\cdot...
  20. K

    Derive cos(A-B) from the law of cosines

    Homework Statement In the chapter about differentiation there is this question: Homework Equations Cosine rule: $$a^2=b^2+c^2-2bc\cos\alpha$$ $$\cos(\alpha-\beta)=\cos\alpha\cos\beta+\sin\alpha\sin\beta$$ The Attempt at a Solution $$a^2=b^2+c^2-2bc\cos\alpha$$ $$d^2=e^2+c^2-2ec\cos\beta$$...
  21. M

    A Deriving Equations of Motion in GR

    Question Background: I'm considering the Eddington-Robertson-Schiff line element which is given by (ds)^2 = \left( 1 - 2 \left(\frac{\mu}{r}\right) + 2 \left(\frac{\mu^2}{r^2}\right) \right) dt^2 - \left( 1 + 2 \left( \frac{\mu}{r} \right) \right) (dr^2 + r^2 d\theta^2 + r^2 \sin^2{\theta}...
  22. Sciencelover91

    How do you derive the mirror equation with a convex mirror?

    Homework Statement Derive the mirror equation for a convex mirror (Si*So=f^2). Do not use a Ray heading toward the center of curvature point (C). Si - distance between the object's image and the focal point. So- distance between the object and the focal point. Do- distance between the mirror...
  23. Y

    Derive KE of rotating ring and disk

    <Mentor's note: Moved from a technical forum and thus no template.> A ring's kinetic energy is integral of 0.5v2 dm. Distance X is rΘ, and Θ is defined as distance traveled/radius, so X is r*distance traveled / r. Velocity V is X divided by time, so V is r*distance traveled / rt, and I define...
  24. N

    I Deriving Weak-Field Schwarzschild Metric from LEFEs

    I am trying to derive weak-field Schwarzschild metric using Linearized Einstein's field equations of gravity: []hμν – 1/2 ημν []hγγ = -16πG/ c4 Tμν For static, spherically symmetrical case, the Energy- momentum tensor: Tμν = diag { ρc2 , 0, 0, 0 } Corresponding metric perturbations for...
  25. D

    A Find EM Potential from EM Tensor | Math Solutions

    Hello, so my question is, if for some metric, we have found (somehow) Fμν, and we know that: Fμν=∂μAν-∂νAμ, how do we find Aν? I tried solving the differential system after imposing the Lorentz gauge ∂μAμ=0 but still, without some initial guess about which components of A are zero, the system...
  26. alan

    Derive approximate expression by regular solution theory

    The question is about to derive an approximate expression by regular solution theory, It is difficult for me to find relevant source on this question. However, the question to me is so vague that I do not know how to answer. What I have tried is to search what the interaction parameter is...
  27. 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...
  28. P

    B What is the Correct Method for Deriving p = γmv?

    I thought this mental experiment: consider an inertial frame of reference solidal to a particle moving with velocity v respect to another inertial frame of reference, i got to find the momentum in the second frame of reference (in the first is 0 since is solidal with the particle) p= m* dx/dt...
  29. Eclair_de_XII

    Using variation of parameters to derive a general solution?

    Homework Statement "By choosing the lower limit of integration in Eq. (28) in the text as the initial point ##t_0##, show that ##Y(t)## becomes ##Y(t)=\int_{t_0}^t(\frac{y_1(s)y_2(t)-y_t(t)y_2(s)}{y_1(s)y_2'(s)-y_1'(s)y_2(s)})g(s)ds## Show that ##Y(t)## is a solution of the initial value...
  30. P

    Derive the wave equation for fields E, B from the potentials

    I'm studying for my electrodynamics exam and one of the past exam questions is: From the scalar and vector potentials, derive the homogenous wave equations for E and B fields in vacuum. I did derive the wave equation for the B field by simply taking the curl of the homogenous wave equation for...
  31. M

    Using Lagrangian to derive the equation of motion

    Homework Statement derive the equation of motion of a mass-spring-pulley system using lagrange's equations. A mass m is connected to a spring of stiffness k, through a string wrapped around a rigid pulley of radius R and mass moment of inertia, I. Homework Equations kinetic energey T = 1/2...
  32. Strife_Cloud

    Stress analysis -- derive equations: bending & yielding

    Problem attached. I would appreciate anyone's help. I am an alloy chemist working on an MS degree in materials engineering and have come to the mechanical engineering part of the program and am feeling a bit behind. Deriving an equation for this case is proving to be difficult for me although...
  33. I

    Kinematics, deriving equations.

    Homework Statement "Derive the equations for position (in terms of acceleration, initial position, initial velocity, and time) and velocity (in terms of constant acceleration, a, initial velocity, v0, and time, t) from the definitions of position, velocity, and acceleration (derivative...
  34. T

    Derive tidal force upon star (approximation: divide star in 2)

    Homework Statement Spherical,homogeneous star with radius R orbiting black hole at distance ## r_p >>R ## .Derive the tidal force acting upon the star by dividing the star into two equal parts and making the necessary approximations. Homework Equations The tidal force equation of ## a \propto...
  35. Cocoleia

    Derive the equation for the shape of an orbit

    Homework Statement I am given this equation: where m and M are masses. I have to obtain the following as a final result: Homework EquationsThe Attempt at a Solution so far, I have done this (This may not be the most efficient or the easiest way, but it is how my professor wants it to be...
  36. bluejay27

    I How can you derive the effective mass?

    I have seen that the energy of the band structure is defined in the following form. How do you obtain this form of the equation? Additionally, how can you obtain the effect mass of the electron? Do you just manipulate algebraically the equation of the energy of the band structure and solve it...
  37. lfdahl

    MHB Can You Derive a Reduction Formula for the Integral $\int \sec^nx dx$?

    Derive a reduction formula for the integral: $\int \sec^nx dx, \;\;\; n \ge 2.$ - without any help from an online integrator.
  38. D

    Derive the equation for kinetic energy and gravitional energ

    Homework Statement A wooden toy mouse of mass (m) is attached to a spring with constant (k) and suspended vertically as shown below. The toy is released at the point the spring is unstretched at position x = +A, passes through equilibrium at x = 0 and the spring’s maximum extension occurs at x...
  39. W

    From the Shockley Ideal Diode Equation derive....

    Homework Statement The Shockley idea diode equation is ##I = I_0( e^{\frac{qV}{kT}}-1)## (1) Where ##I_0## is the reverse bias saturation current, ##q## is the charge of an electron, ##T## is temperature in Kelvin and ##k## is Boltzmann's constant. For large reverse voltages, ##I## is...
  40. S

    Can we derive quantification of energy mathematically?

    I'm studying for my introduction to modern physics exam, and reading about the ultraviolet catastrophe and why equipartition theorem stops working to explain blackbody emissions for high frequencies I was thinking if we could use the theorem to arrive at the quantification of energy (probably...
  41. cementite

    Derive an expression for the deflection between two forces

    Homework Statement Two rods of the same material, of equal length l, and of cross section A and 2A respectively, are mounted between two rigid (i.e., nondeformable) cross frames. The frames are pulled by a pair of forces P, located at distance x from the thin bar. Derive an expression for the...
  42. P

    I Is there any way to derive the time dilation formula?

    I've already read the derivation in which we use the light pulse clock kept in a spacecraft such that the light pulse follows a zig-zag motion due to motion of the spacecraft being perpendicular to motion of the light pulse. Then, we apply Pythagoras theorem to derive the formula. BUT this...
  43. O

    Derive the energy required for an ideal refrigerator

    Homework Statement Show that the energy, E, that needs to be supplied to an ideal refrigerator to cool a mass M with specific heat C by \DeltaT from an initial temperature T_i is: E\sim \frac{MC\Delta T^2}{2T_i} Homework Equations Carnot efficiency where T_i is the starting higher temperature...
  44. L

    How to derive this heat input equation?

    There's one equation that I've seen being used already, which by itself is quite simple, but I can't understand where it comes from. The context is as follows: suppose we have one heat engine operating between systems A and B whose temperatures are T_A>T_B. Let's suppose further that the...
  45. JohnTravolski

    Derive an expression for the angle φ (Kinematics Problem)

    I'm really lost on this one. I'm really not sure how to get started on this. I started it out as a force problem and solved for ax = g*cos(theta). I then integrated that (treating it like a constant) from zero to D to find my initial velocity at the time the block reaches the edge of the...
  46. J

    I How to derive full solar sprectrum from gamma rays

    I understand that the fusion of hydrogen to helium in our sun's core generates gamma rays. My question is how are these gamma rays transformed to the full spectrum of photons that we that we observe from earth?
  47. O

    I How to logically derive the total derivative formula?

    Consider this equation: f(x(t),y(t))=2(x(t))^2+x(t)y(t)+y(t) One way to calculate df/dt is directly using the chain rule: \frac{df}{dt}=4x(t)\frac{dx}{dt}+\frac{dx}{dt}y(t)+\frac{dy}{dt}x(t)+\frac{dy}{dt} \frac{df}{dt}=(4x(t)+y(t))\frac{dx}{dt}+(x(t)+1)\frac{dy}{dt} Another way is by using...
  48. Nipuna Weerasekara

    B How is the Wave Function Derived in Quantum Mechanics?

    Everybody knows what is the Wave Function is. $$\Psi=\space e^{i(kx-\omega t)}$$ or $$\Psi=\space cos{(kx-\omega t)} \space - \space isin{(kx-\omega t)}$$ But can anyone tell me how it is derived. Since Schrodinger Equation is derived so easily using this Wave Function. I think it is necessary...
  49. C

    Help me derive the Doppler effect ratio

    Homework Statement I'm watching this lecture and wanted to attempt to derive the expression for ΔTo/ΔTs Homework Equations ΔTo = ΔTs + VΔTo / U The Attempt at a Solution I have worked out that ΔTs = 1-V / U, however I'm stuck trying to get ΔTs / ΔTo because of the ΔTo on both sides of the...
  50. Mr Davis 97

    Derive vector that moves uniformly from one point to another

    Homework Statement Consider two points located at ##\vec{r}_1## and ##\vec{r}_2##, and separated by distance ##r = |\vec{r}_1 - \vec{r}_2|##. Find a time-dependent vector ##\vec{A} (t)## from the origin that is at ##\vec{r}_1## at time ##t_1## and at ##\vec{r}_2## at time ##t_2 = t_1 + T##...
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