Length Definition and 1000 Threads

Length is a measure of distance. In the International System of Quantities, length is a quantity with dimension distance. In most systems of measurement a base unit for length is chosen, from which all other units are derived. In the International System of Units (SI) system the base unit for length is the metre.
Length is commonly understood to mean the most extended dimension of a fixed object. However, this is not always the case and may depend on the position the object is in.
Various terms for the length of a fixed object are used, and these include height, which is vertical length or vertical extent, and width, breadth or depth. Height is used when there is a base from which vertical measurements can be taken. Width or breadth usually refer to a shorter dimension when length is the longest one. Depth is used for the third dimension of a three dimensional object.Length is the measure of one spatial dimension, whereas area is a measure of two dimensions (length squared) and volume is a measure of three dimensions (length cubed).

View More On Wikipedia.org
Recent contents Top users
  1. 1

    What is the solution to finding d(x) without using trigonometry?

    Homework Statement Attached Homework Equations The Attempt at a Solution I am to provide a solution without using any trigonometry or calculus, but I can't find a way. To clarify, I must find d(x). Involving trig, the problem is trivial, as the angle "A" is equal to...
  2. A

    What is Correlation Length and How is it Related to Surface Roughness?

    What is "Correlation length"? Hi everyone, I want to know meaning of "correlation length". Correlation function is usually used in statistics, so I think correlation length also similar meaning. But some paper used correlation length to explain roughness factor. Plz, anyone reply...
  3. 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...
  4. J

    CONVERGENT nozzles contraction ratio and length

    I am currently designing a convergent nozzle for use in experiments and wanted to check something: Will the pressure and density of the flow always expand to ambient (following the isentropic relations) when it reaches the nozzle exit regardless of nozzle contraction ratio and length? Any...
  5. Y

    Problems with Proper Length and Proper Time in SR

    I have just started studying Special Relativity in class and the concepts of Proper Length and Proper Time are giving me some issues. I understand the basics of length contraction and time dilation, but the idea of this "proper" time and length is giving me problems. One example in particular...
  6. J

    Is length contraction real or just a matter of perspective?

    I would appreciate views on the following understanding of length and distance in SR, restricted here to inertial movement. This is the beginning of a follow up to the thread: https://www.physicsforums.com/showthread.php?t=724025 1. The spatial length of an object is the spatial separation...
  7. applestrudle

    Length of a 3D parametric function

    Homework Statement find the length of a circular helix expressed in parametric form x= cos(t), y=sin(t) and z = t from t = 0 to t =2pi Homework Equations L = integrate ds (ds)^2 = (dx)^2+(dy)^2+(dz)^2 The Attempt at a Solution I got to ds = (1 + (dt)^2)^0.5 but I can't...
  8. applestrudle

    What is the Length of a Curve with a Cubic Equation?

    Homework Statement Find the length of the curve y = x^3/a^2 + a^2/12x between a and a/2 Homework Equations Length L = integrate (1+ dy/dx)^2)^0.5 The Attempt at a Solution I got to integrate (9x^4/a^2 + 1/2 + a^4/144x^4)^0.5 but I can't simplify it
  9. G

    Graduating Engineer - Should I Take a 1 Year Job?

    I will be graduating with an engineering degree (mechanical) in May of 2014. The city that I currently live in is not where I want to stay after I graduate; however, my wife is well established in her career and it makes sense for us to stay here for a year or so in order to save up money etc...
  10. NotAMethDealer

    Length Contraction Affect on Mass: Physics Explained

    If an object is going at near C(light velocity) and undergoes length contraction. Does the mass fluctuate?I apologize if it is an obvious question but I'm a little rusty on my physics.
  11. H

    Solve for the slope and length of a line segment

    The problem is to a.) solve for the slope m of the hypotenuse of the right triangle indicated by the shaded area, and b.) solve for the length of the hypotenuse, if possible. I made a mistake in transcribing the problem onto paper, the line of course extends indefinitely but the shaded area and...
  12. S

    Statistical physics - average length of polymer

    Homework Statement A polymer consits of ##10^{20}## monomers, each 2 nm long. One end of the polymer is hanged at the ceiling on the other end, we have a load of ##4\cdot 10^{-10}g##. Calculate the average potential energy!Homework Equations The Attempt at a Solution Well... I don't know...
  13. N

    Length change of diagonal in deformable triangle

    Hi I have a problem understanding a figure in my lecture notes. The figure is the following one It shows the deformation of a triangular element from time t to time t+dt: So at t it is a isosceles triangle and at t+dt it is deformed. According to my lecture notes (page 16, eq. 28), the...
  14. A

    Rijke tube: Why Sound is maximum when heated 1/4th length from bottom

    Why is it that the maximum sound coming from a Rijke tube happens only when heated wire gauze is placed at 1/4th the length of the tube from the bottom. According to Rayleighs criterion(copy pasted) "If heat be periodically communicated to, and abstracted from, a mass of air vibrating in a...
  15. Dilatino

    Why does the Schwinger parameter correspond to proper length?

    I have just learned from nice article http://motls.blogspot.com/2013/12/edward-witten-what-every-quantum.html that the propagator of a massive particle can be rewritten as an integral over the so-called Schwinger parameter t as $$ \frac{1}{p^2 + m^2} = \int\limits_0^\infty dt...
  16. PhizKid

    Length of a polynomial vector?

    Homework Statement S = {1, x, x^2} Find ||1||, ||x||, and ||x^2||.Homework Equations ##\sqrt{v \cdot v}##The Attempt at a Solution I don't know the components of each vector, so how can I perform the dot product?
  17. 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...
  18. M

    Buckling question finding equivalent length and I

    Hello, I am having trouble understanding why the equivalent length in buckling problems, as well as the moment of inertia, change depending on what plane of buckling you are looking for, and how to calculate the moment of inertia in a particular plane
  19. S

    Optical path length change due to absorption

    Hey, so I am trying to figure out the optical path length change of an optical fiber due to absorption. I'll post what I have so far and let me know if I have done anything wrong or if you have suggestions. so the optical path length is L' = nL (L' is optical path length, n is refractive...
  20. Superposed_Cat

    Length Contraction oes the object or travel distance shrink?

    Length Contraction:Does the object or travel distance shrink? I had always thought that length contraction meant that the object itself shrunk but I stumbled across an article where they said "Because of length contraction the photon doesn't travel any distance at all. Which is it? Any help...
  21. Y

    Solve Length of Solenoid Homework: Find N & L

    Homework Statement (a) What would have to be the self-inductance of a solenoid for it to store 9.3 J of energy when a 1.56-A current runs throught it? (b) If this solenoid's cross-sectional diameter is 3.85 cm, and if you could wrap its coils to a density of 10 coils/mm, how long would...
  22. T

    Length contraction clarification

    Consider two iron rods of about 10 metres separated by 10 metre. They are in series position and not connected in anyway. If the rods are passing nearby an observe with a velocity of 90% speed of light, then what would he observe? 1) does the separation between the rods (ie 10m) undergo length...
  23. U

    What is the minimum length chord of a circle passing through a specific point?

    Homework Statement px+qy=40 is a chord of minimum length of the circle (x-10)^2 + (y-20)^2 = 729 . If the chord passes through (5,15), then p^{2013}+q^{2013} is equal to Homework Equations The Attempt at a Solution Let chord length be L \frac{L}{2} = 729-...
  24. T

    Do length contraction affects accelerating objects?

    Suppose I'm standing on Earth and i see an iron rod accelerating through space with a rate of 1m/s^2. Will it undergo length contraction after reaching a speed nearly to the c? Will there be any deformations to a spinning disk?
  25. F

    How does this affect the length contraction paradox?

    Hi, As is well known, Relativity claims that a rod of a given proper length will appear length contracted when measured by a moving observer. Now consider a rod of length L and observer initially at rest relatively to it, with one end of the rod at the observer's coordinate x1(0) and the...
  26. B

    Problem caused by length contraction and relativity and personal expla

    The problem has been shown in the picture. Because of relativity, both the guys on the ground and on the vehicle would observe length contraction. So the destination of the guy on the vehicle---the galaxy, would be more closed to him. If the vehicle is replaced with the light, which means the...
  27. R

    Finding the bond length of hydrogen theoretically

    If the bond length of two atoms is the distance where the force of repulsion is equal to the force of attraction, then one could figure out what the bond length of H2 is by setting the net force of attraction to the net force of repulsion and solving for distance. However when I try this ...
  28. C

    Solving for Final Velocities and Min Length of m2

    Homework Statement (Diagram of problem is given in attachment) m2 is stationary The coefficient of kinetic friction on m2 is 0.2 while the ground below m2 has a coefficient of friction of 0. a) Find the final velocity of both objects if m1 moves at the same v as m2 b)Find the minimum length...
  29. H

    Finding the length of an arc of a parabola

    Homework Statement y^2 = x from (0,0) to (1,1) Homework Equations L = ∫√(1+[g'(y)]^2) dy The Attempt at a Solution So this is a problem in my textbook that has been bothering me because I can't seem to come up with the same answer. 1. [bounds 0 to 1] 1/2∫ sec^3θ was obtained...
  30. Z

    Perspective on Relativity and Length Contraction

    Hello All, I like to think that I have a decent background in physics and related material, but I confuse myself quite easily on, well, everything. I guess I think about it too much, really. So feel free to give complex answers and I will do my best to follow along accordingly. Anyways, here...
  31. A

    Finding frequency if you know mass and length of rope.

    Homework Statement A girl with a mass of 40 kg is swinging from a rope with a length of 2.8 m. What is the frequency of her swinging? Homework Equations I could find the period of the situation and then from there could calculate the frequency. For the period I'm not sure what...
  32. M

    Spacetime/Proper Length

    In special relativity, length dilation is defined as follows: X' = X0√(1 - V2/c2), where X' is the apparent/dilated length and X0 is the "proper length" Therefore proper length: X0 = X'/√(1 - V2/c2), where c > V > -c I read a book on the spacetime approach to relativity using the...
  33. R

    Polar integration - Length and Area of curve

    The area of a polar curve is given by A=(1/2)∫ r2 d (theta). this can be interpreted as δA= ∏r2δ(theta)/2∏ (treating the area element as the area of a sector of a circle with angle δ(theta).) taking limit of δ(theta)→0, dA= ∏r2 d(theta)/2∏=1/2 (r2d(theta) ) there fore A=1/2∫r2 d(theta)...
  34. N

    Interrelationship between power of 2 and integer length

    Hello, I was wondering if someone knew the equation which describe the exact or statistical relation between the length(# of digits) of a power of 2 based on it's power. I plotted 200 of the powers in mathematica and I get a fairly straightforward staircase plot. I'm just wondering what's the...
  35. M

    What is the largest wavelength for maximum sound intensity?

    Homework Statement Two sources, A and B, emit a sound of a certain wavelength. The sound emitted from both sources is detected at a point away from the sources. The sound from souce A is a distance d from the observation point, whereas the sound from source B has to travel a distance of...
  36. I

    Gravity causing distances smaller than a Plack length?

    This is a thought experiment that just popped up in my head, please excuse any layman inaccuracies. Imagine the largest, most massive galaxy in the entire universe. Let's hypothesize that it is at a great distance from earth, beyond the edge of the observable universe. Now, since all objects...
  37. A

    How can the length of a normal vector matter?

    Homework Statement Homework Equations The Attempt at a Solution Solution: Graph: For part a, I understand mathematically why the value of c matters. What I don't understand is how it can possibly matter intuitively. I get that ##\overrightarrow { \nabla }...
  38. C

    Finding total length of a parametric curve

    Homework Statement Find the total length of the curve t --> (cos^3(t), sin^3(t)), and t is between 0 and ∏/2 where t is in radians. Find also the partial arc length s(t) along the curve between 0 and ∏/2 Homework Equations The length is given by: S = ∫\sqrt{xdot^2 + ydot^2} dt...
  39. M

    Multivariable calculus: Length of curve

    Homework Statement Find the length of the curve traced by the given vector function on the indicated interval. r(t)=<t, tcost, tsint> ; 0<t<pi Homework Equations s= ∫||r'(t)||dt The Attempt at a Solution r'(t) = <1, -tsint + cost, tcost + sint> s= ∫||r'(t)||dt ||r'(t)|| =...
  40. C

    Length on vibrating section of violin

    Homework Statement A particularly beautiful note reaching your ear from a rare Stradivarius violin has a wavelength of 39.1 cm. The room is slightly warm, so the speed of sound is 344 m/s. If the string's linear density is 0.560g/m and the tension is 160N , how long is the vibrating section...
  41. S

    From what point is the focal length of a thick lens measured?

    I'm designing an eyepiece for fun and want to be accurate. I just realized my physics book equations are approximated for thin lenses only. Suppose I have a convex convex lens or a plano convex lens, lateral parallel rays coming from one side or the other, and a focal point on the opposite...
  42. N

    Calculate the change in length of year due to change in Sun's mass

    EDIT: It seems that just after posting this, my professor decided this problem is too difficult for us to be responsible for. I can't delete this question, so don't feel obligated to answer it. But who knows? Maybe someone else out there has the same question. Homework Statement The Sun...
  43. W

    Optimizing Ramp Length for Unicycle Climbing

    Homework Statement A person on a unicycle has a total weight of 900N. They need to climb to a height of one meter. If we build the ramp for a minimum pushing force of 50N, how long must the ramp be? m=91.7kg w=900N F1=50N Ry=1m Rx=? Rxy=? θ=? Homework Equations .5mv2=mgh F1=mgsinθ The...
  44. U

    What are the possible values of a for the least possible length of latus rectum?

    Homework Statement If abscissa and ordinate of vertex of parabola y^2+2ax+2by-1=0 are equal then least possible length of latus rectum is Homework Equations The Attempt at a Solution The give equation can be rewritten as \left( y+b \right) ^2 = -2a\left\{ x-\dfrac{1+b^2}{2a}...
  45. P

    Scalar product used for length?

    I got asked how the scalar product can be used to find the length of a vector? Could someone please explain
  46. D

    Finding the Length of a Chord on a Circle

    Homework Statement Find the length of the chord which the circle 3x^2+3y^2-29x-19y+56=0 cuts off from the straight line x-y+2+=0. Find the equation of the circle with this chord as diameter Homework Equations x^2+y^2+2gx+2fy+c=0 The Attempt at a Solution I can solve the second part...
  47. 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...
  48. R

    How can I find the length of a day on Jupiter from wavelengths?

    The question is: the wavelength of a spectral line on the left edge of Jupiter's equator is 499.98 nm, and the right edge is 500.02 for the same spectral line, what is the length of jupiter's day (in hours)? I know that its 10 hours but I need to show my work. I tried using many different...
  49. S

    How Do You Calculate Cable Length and Vector Forces in Statics?

    Homework Statement The window is held open by the cable AB. Determine the length of the cable and express the 30N acting at A along the cable as a Cartesian vector. http://img802.imageshack.us/img802/9599/ru5y.jpg Homework Equations vector(F) = FuAB The Attempt at a Solution Here's my...
  50. C

    Change in length of wire after adding a load

    Homework Statement Please refer to the image attached. I don't understand why can they just take 1.8m as the original length, since there is already a load hanging there. My calculations yield the value of strain to be e/L, but in the answer it is e/1.8. Please explain this to me. Homework...
Back
Top