Arc length Definition and 286 Threads

Arc length is the distance between two points along a section of a curve.
Determining the length of an irregular arc segment is also called rectification of a curve. The advent of infinitesimal calculus led to a general formula that provides closed-form solutions in some cases.

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  1. Euler2718

    Trigonometry Arc Length Problem

    First I'd just like to point out that I'm taking calculus and advance pre-calculus simultaneously (kind of a stupid system) and this is a problem in the pre-calc. 1. Homework Statement 2. Homework Equations Let 'a' be arc length. a=\theta r a = \int_{a}^{b} \sqrt{1+[f'(x)]^{2}} dx...
  2. P

    Arc Length: Definite and Indefinite Integration

    Several authors state the formula for finding the arc length of a curve defined by ##y = f(x)## from ##x=a## to ##x=b## as: $$\int ds = \int_a^b \sqrt{1+(\frac{dy}{dx})^2}dx$$ Isn't this notation technically wrong, since the RHS is a definite integral, and the LHS is an indefinite integral...
  3. C

    Solving Catapult Project: Finding Spring Constant

    I'm doing a catapult project but I'm sort of confused. I need to find the spring constant in order to get the elastic potential energy. The force of pulling back the catapult lever to 36 degrees above the horizontal is 4.2 N. Right before the lever is at rest, 90 degrees, the force is 1.4 N. One...
  4. Z

    MHB How to Calculate Arc Length for a 124° Angle in a Circle?

    A circle has a radius of 10cm. Find the length s of the arc intercepted by a central angle of 124° . Do not round any intermediate computations, and round your answer to the nearest tenth. How do I do this?
  5. ArcanaNoir

    Arc length of intersecting circles

    Homework Statement My class is working through chapter 2 of Newman's Analytic Number Theory text (on partitions). We have come to a part where he states that "elementary geometry gives the formula" (for the length of arc A) 4r\text{arcsin}\frac{\sqrt(2)(1-r)}{\sqrt(r)} We are attempting to...
  6. admbmb

    Conceptual trouble with derivatives with respect to Arc Length

    Hi, So I'm working through a bunch of problems involving gradient vectors and derivatives to try to better understand it all, and one specific thing is giving me trouble. I have a general function that defines a change in Temperature with respect to position (x,y). So for example, dT/dt would...
  7. A

    Find the arc length parametrization of a curve

    Homework Statement Find the arc length parametrization of the curve r = (3t cost, 3tsint, 2sqrt(2)t^(3/2) ) . Homework Equations s(t)=integral of |r'(t)| dt The Attempt at a Solution I was able to get the integral of the magnitude of the velocity vector to simplify to: s(t) = integral of...
  8. S

    Question about circle arc length formula

    Now i haven't checked yet whether or not this is correct, but the formula for the length of an arc that subtends a central angle can also be expressed this way: AC/360 Where: A: Central Angle C: Circumference Is this correct? Thank you for your help.
  9. L

    Calculating Arc Length of a Curve: A Calculus II Problem

    Homework Statement Find the exact length of the curve: y= 1/4 x2-1/2 ln(x) where 1<=x<=2 Homework Equations Using the Length formula (Leibniz) given in my book, L=Int[a,b] sqrt(1+(dy/dx)2) I found derivative of f to be (x2-1)/2x does that look correct? The Attempt at a Solution I found f'...
  10. C

    Calculating Arc Length of a Curve: y^2 = x^3, (1,-1) to (1,1)

    Homework Statement A curve has the equation y2 = x3. Find the length of the arc joining (1, - 1) to (1, 1). Homework Equations The Attempt at a Solution I took the integral of the distance and tried to evaluate from -1 to 1. L = [intergral (-1 to 1) sqrt (1+(dy/dx x^3/23/2)2 dx] Evaluated I...
  11. C

    Find Arc Length of Particle Moving on Curve

    Homework Statement Find the length of the path traced out by a particle moving on a curve according to the given equation during the time interval specified in each case. The equation is r(t) = a(cos t + t sin t)i + a(sin t - t Cos t)j, 0</=t</=2pi, a>0Homework Equations Arc length =...
  12. I

    MHB Arc Length C: Origin to (6,18,36)

    let C be the curve of intersection of the parabolic cylinder $x^2=2y$ and the surface $3z=xy$. find the exact length of C from the origin to the point (6,18,36). please help! this is the last question i have left from this assignment and i have no idea how to do it. i have grading to do and a...
  13. S

    Polar Arc Length: Solve Integral of r=6cos6θ

    Homework Statement Find the arc length of one of the leaves of the polar curve r= 6 cos 6θ. Homework Equations L = ∫sqrt(r^2 + (dr/dθ)^2) dθ (I use twice that since the length from 0 to π/12 is only half the petal) The Attempt at a Solution I seem to get an integral that can't be...
  14. Shackleford

    What is the arc length parametrization of α(t) and why is the s so tiny?

    Of course, I need to find the first derivative and integrate its norm. α'(t) = (1, 0, (1/2)t^2 - (1/2)t^-2) ∫ [1 + (1/4)t^4 + (1/4)t^-4]^(1/2) dt, t = 1 to t = 3. Have I simply forgotten useful integrals? α'(t) = (e^t, -e^-t, root2) ∫ [e^2u + e^-2u + 2]^(1/2) du, u = 0 to u = t.
  15. S

    MHB Arc Length and Rotation, Please Explain this problem

    EDIT: Okay now that the admin has cleaned up my mess, please scroll down to see the correct image and the question on the 3rd post in this thread.
  16. I

    MHB Find arc length starting from P_0

    find the arc length function for the curve $y=2x^{3/2}$ with starting point $P_{0}(1,2)$. how do i do this? this is what I've done so far. $y'=3\sqrt{x}$ $1+(3\sqrt{x})^2=9x+1$ $\int_{a}^{b} \ \sqrt{9x+1},dx$ what's my a and what's my b?
  17. F

    Is the Area Under a Curve Equal to its Arc Length?

    I learned in my calc 1 class that to calculate the arc length of a curve, we are to compute the integral of the function. For example, the integral of a function that describes the path of a thrown baseball would give the total distance traveled by the baseball (I hope I'm using the term arc...
  18. D

    Troublesome Arc Length Problem

    1.) The problem is: Find the arc length of f(x)= x^3/3-1/(4x) from x=1 to 2 2.) Relevant formulas: ds = √(1+(dy/dx)) abs(L) = ∫ds 3.) My work so far: f'(x)= x^2+1/(4x^2) abs(L) = ∫(from 1 to 2) √(1+(x^2+1/(4x^2))^2 dx = ∫(from 1 to 2) √(1+(x^4+1/2+1/(16x^4)) dx = ∫(from 1...
  19. A

    Solving for Spiral Arc Length: A Scientist's Approach

    So here's a little background for the question: I have an arc that covers 3/4s of a circle (so it's not quite a full circumference) such that the radius from the center of the arc varies with respect to the angle (dR/d(theta)) (and it can be either positive or negative, but not constant). I am...
  20. N

    Difficult simplification for Arc length integral

    Homework Statement Find the length of the curve x = 3 y^{4/3}-\frac{3}{32}y^{2/3}, \quad -64\le y\le 64Homework Equations Integral for arc length (L): L = \int_a^b \sqrt{1 + (\frac{dy}{dx})^{2}} dx The Attempt at a Solution Using symmetry of the interval and the above integral for arc length...
  21. E

    Solving Arc Length Integral with Trigonometric Substitution

    ∫sqrt(x^4/4 + 1/(x^4) + 1/2) dx from x = 1 to 4 Could someone help me solve this? I can't seem to find a substitution that works, or find the square root of (x^4/4 + 1/(x^4). Any help would be very appreciated. Thanks in advance!
  22. S

    MHB Is Finding the Arc Length of a Curve the Same as Finding the Length?

    This may seem like a dumb question, but is finding the "arc length" of a curve and finding the "length" of a curve the same thing? Just worded differently?
  23. A

    Arc Length Units: Explained & Solved Problem

    Hello, I solved the arc length for a particular problem. However, what is the unit of arc length if the units of the velocity vs time graph are m/s vs s? I am really confused.
  24. Y

    Why Does the Magnitude of r'(s) Equal 1 When s is the Arc Length Parameter?

    1. The problem statement, all variables and given/known If C is a smooth curve given by r(s)= x(s)i + y(s)j + z(s)k Where s is the arc length parameter. Then ||r'(s)|| = 1. My professor has stated that this is true for all cases the magnitude of r'(s) will always equal 1. But he wants me...
  25. S

    Finding arc length using integration

    Find the length of the positive arc of the curve y=cosh^{-1}(x) (for which y≥0) between x=1 and x=\sqrt{5}. My attempt: x=cosh(y) → \frac{dx}{dy} = sinh(y) → (\frac{dx}{dy})^{2}=sinh^{2}(y), so ds=dy\sqrt{1+sinh^{2}(y)}, therefore the arc length is S=\int_{y=0}^{y=cosh^{-1}(\sqrt{5})} cosh(y)...
  26. R

    MHB Find arc length given chord, radius

    The solution to this question (whose answer is pi) is eluding me: The radius of a circle is 3 feet. Find the approximate length of an arc of this circle, if the length of the chord of the arc is 3 feet also.
  27. A

    MHB Integration question (obtained from arc length question)

    how do i integrate the function sqrt(1 + 1/2(y^1/2 - y^(-1/2))^2) from 0 to 1??
  28. M

    Complicated Arc length problem

    Homework Statement The length L or the curve given by \frac{3y^{4}}{2}+\frac{1}{48y^{2}}-5 from y=1 to y=2 Homework Equations The Attempt at a Solution Setting up the formula is easy. First I found the derivative of f(y) which is: f'(y)=6y^{3}-\frac{1}{24y^{3}} Then I plugged...
  29. ThomasMagnus

    Relating Arc Length and Standing Wave Patterns

    Homework Statement I am currently reviewing the physics of 'standing waves on a string'. I know that for the nth harmonic, the length of the 'string' is \frac{n\lambda}{2}. Instead of just memorizing these, I have been trying to apply my knowledge of Calculus to figure out why these numbers...
  30. L

    Calc 2: Arc Length from 0-π/4 for James Stewart 7th Ed.

    Ello every one, i have interesting question. Any one who has james stewert 7th edition calc book I am on secotion 8.1 studying for an exam. number 13 of 8.1 says this y= ln(secx) find arc length from 0-pi/4 here is what i do first in my opinion. y`= 1/sec(sectan) y`= tanx...
  31. J

    Calculate the arc length of the vector function

    Homework Statement Calculate the arc length of <2t,t^2,lnt> from 1=<t=<e Homework Equations Arc length=∫√{(x')^2 + (y')^2 + (z')^2} The Attempt at a Solution So I have gotten to this point: ∫√{4 + 4t^2 + \frac{1}{t^2}} Am I on the right track, and if so, how do I integrate that?
  32. C

    Arc length parametrisation question (error in notes?)

    This is from my course notes http://img28.imageshack.us/img28/2630/ckyl.jpg In line 3, there's the integral \int_0^t ||y'(s)||ds which represents the length of the curve as a function of t (which I am thinking of as time). Here, I think s is a dummy variable for time. The equation in line...
  33. PsychonautQQ

    Finding the Arc Length Parameterization of a Vector Function

    Homework Statement Find the arc length parameterization of r(t) = <(e^t)sin(t),(e^t)cos(t),10e^t>The Attempt at a Solution so I guess i'll start by taking the derivative of r(t)... r'(t) = <e^t*cos(t) + e^t*sin(t), -e^t*sin(t) + e^t*cos(t), 10e^t> ehh... now do I do ds = |r'(t)|dt and...
  34. PsychonautQQ

    Finding arc length of polar Curve

    Homework Statement Find the arc length of polar curve 9+9cosθ Homework Equations L = integral of sqrt(r^2 + (dr/dθ)^2 dθ dr/dθ = -9sinθ r = 9+9cosθ )The Attempt at a Solution 1. Simplifying the integral r^2 = (9+9cosθ^2) = 81 +162cosθ + 81cos^2(θ) (dr/dθ)^2 = 81sin^2(θ)...
  35. Fernando Revilla

    MHB Calculating Arc Length for Curve c(t) = (t,t,t^2)

    I quote a question from Yahoo! Answers I have given a link to the topic there so the OP can see my response.
  36. T

    Arc length of a regular parametrized curve

    Given t\in Ithe arc length of a regular parametrized curve \alpha : I \to \mathbb{R}^3 from the point t_0 is by definition s(t) = \int^t_{t_0}|\alpha'(t)|dt where |\alpha'(t)| = \sqrt{(x'(t))^2+(y'(t))^2+(z'(t))^2} is the length of the vector \alpha'(t). Since \alpha'(t) \ne 0 the arc length s...
  37. T

    Arc length of a regular parametrized curve

    Given t\in Ithe arc length of a regular parametrized curve \alpha : I \to \mathbb{R}^3 from the point t_0 is by definition s(t) = \int^t_{t_0}|\alpha'(t)|dt where |\alpha'(t)| = \sqrt{(x'(t))^2+(y'(t))^2+(z'(t))^2} is the length of the vector \alpha'(t). Since \alpha'(t) \ne 0 the arc length s...
  38. J

    Far Field lens Imaging…Does k-wave number follow arc length equation?

    If we are imaging light in the far field region. We have three situations/relations (illustrated below): Arc Length: We know the distance subtended (S) by the light ray in a lens-less system will be proportional to R (distance to the screen) and theta; simple, especially if theta is very...
  39. B

    Arc Length of y = x^3/6 + 1/2x on [1/2, 2]

    Homework Statement Find the arc length of the graph, on the interval [1/2, 2], of y = \frac{x^3}{6} + \frac{1}{2x} Homework Equations s = \int^b_a \sqrt{1 + [f'(x)]^2}dx The Attempt at a Solution I began with s = \int_{1/2}^2 \sqrt{1 + (\frac{x^2}{2} - \frac{1}{2x^2})^2}dx...
  40. R

    Solving an equation: finding the arc length

    hello every body .. According to the picture: Circle radius (Radius) and height (High) is known to us. Given that the height of the draw the tangent line , I looking for the equation for length of the arc (Arc Length) was calculated based on height changes. (sorry for my written...
  41. P

    I'm struggling to compute arc length (multivariable calculus)

    Homework Statement Find the arc length of the curve (t) = (1; 3t2; t3) over the interval 0  t  1. Homework Equations L=sqrt(f'(t)^2+g'(t)^2+...+n'(t)^2) (integrated from a to b) int(udv)=uv-int(vdu) The Attempt at a Solution Seems like it should be fairly straightforward-- the...
  42. F

    Finding Arc Length in Optimization Problem

    Homework Statement Joe is traveling from point A across a circular lake to a cabin on the other side at point B. The straight line distance from A to B is 3 miles and is the diameter of the lake. He travels in a canoe on a straight line from A to C. She then takes the circular trail from C to...
  43. C

    MHB How Do You Calculate the Arc Length of a Baseball's Trajectory?

    The centerfield fence at a ballpark is 10 ft high and 400 ft from home plate. The ball is 3 ft above the ground when hit, and leaves with an angle theta degrees with the horizontal. The bat speed is 100 mph. Use the parametric equations x = (v0cos(theta))t y = h + (v0sin(theta))t - 16t^2 a...
  44. Y

    Question on Arc Length parameterization.

    This is an example in book by Howard Anton: Vector form of line is ##\vec r=\vec r_0+t\vec v## where ##\vec v## is parallel with the line. So both ##\vec r## and ##\vec r_0## are POSITION VECTORS. To change parameters, 1)Let u=t ##\Rightarrow\; \vec r=\vec r_0+u\vec v##. 2) ##\frac {d\vec...
  45. Petrus

    MHB How to calculate the arc length of a function using integration by parts?

    Calculate the length of the curve We got the formula \int_a^b\sqrt{1+[f'(x)]^2} and f'(x)=\frac{x}{36}-\frac{9}{x} <=> \frac{x^2-324}{36x} so now we got \int_9^{9e}\sqrt{1+(\frac{x^2-324}{36x})^2} we can rewrite that as \int_9^{9e}\sqrt{1+\frac{(x^2-324)^2}{1296x^2}} then do integration by part...
  46. stripes

    A biconditional statement for arc length of a function

    Homework Statement Show that \gamma : [a, b] \rightarrow \Re^{2} is a parameterization of \Gamma if and only if the length of the curve from \gamma(a) to \gamma(s) is s - a; i.e., \int ^{s}_{a} \left| \gamma ' (t) \right| dt = s - a. Homework Equations The Attempt at a Solution Part 1...
  47. stripes

    Prove that any curve can be parameterized by arc length

    Homework Statement Prove that any curve \Gamma can be parameterized by arc length. Homework Equations Hint: If η is any parameterization (of \Gamma I am guessing), let h(s) = \int^{s}_{a} \left| \eta ' (t) \right| dt and consider \gamma = \eta \circ h^{-1}. The Attempt at a Solution...
  48. icesalmon

    Symmetric arc length of ln(x) and e^x

    Homework Statement Explain why ∫(1+(1/x2)1/2dx over [1,e] = ∫(1+e2x)1/2dx over [0,1] The Attempt at a Solution The two original functions are ln(x) and ex and are both symmetrical about the line y = x. If I take either of the functions and translate it over the line y = x the two...
  49. E

    How do I calculate arc length using the arc length equation?

    Homework Statement Homework Equations The arc length equation? The Attempt at a Solution I don't know where to begin.
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