Point Definition and 1000 Threads

The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at a standard pressure such as 1 atmosphere or 100 kPa.
When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point or crystallization point. Because of the ability of substances to supercool, the freezing point can easily appear to be below its actual value. When the "characteristic freezing point" of a substance is determined, in fact the actual methodology is almost always "the principle of observing the disappearance rather than the formation of ice, that is, the melting point."

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  1. Conductivity

    Understanding Torque: Choosing the Point of Rotation for Rotational Motion

    I have a little bit of confusion here :c I don't understand something about torque. I can prove every definition about rotational motion if I assume that a point mass is moving in a circular motion. and if I also define a point of rotation I don't need an object to rotate in order to have...
  2. D

    Components of the equivalent moment at a point

    1. The problems: The questions are to find the x, y and z components of the equivalent MOMENT at point A in both diagrams. For the green block, I found the y and z components of the equivalent force at point A are -39.04kN and 15.48kN respectively. The Attempt at a Solution For the first...
  3. Epoch

    Electricity: electric field in a point Between Two Charges

    Homework Statement I've seen many books writing the cosine rule like this: a^2 = b^2 + c^2 - 2bc cos A My electricity textbook for an electric field in a point between two charges says this: E resultant = root[E1^2 + E2^2 + 2*E1*E2*cos(angle between E1 and E2)] In the first equation it is -2...
  4. M

    Finding electric potential given two point charges

    Homework Statement Find the potential at points P1, P2, P3, and P4 in the diagram due to the two given charges. Homework Equations VP =k∑qi/ri p = q ⋅ d The Attempt at a Solution I'm not sure how to approach the problem. I thought about using that given equation four times and adding it all...
  5. parshyaa

    I Prove that only one straight line passes through two point

    I was just thinking of basic definitions of geometry and i came to this question, so how could i prove that only one straight line passes through two distinct points.
  6. P

    B The Problem with Point Particles

    There is a clear problem with the continuing belief that (any) point particles exist in nature. Quantum mechanics, relativity and even classical physics all forbids this approach. Let's explore why: 1). Quantum theory forbids point particles, because points themselves do not make sense in phase...
  7. T

    Pore pressure at different point ( seepage in soil)

    Homework Statement I am not sure how to get Nd in this question ( circled part) I am not sure the exact location of the point where the author want to find the pore pressure . Can someone help ? This notes is confusing Homework EquationsThe Attempt at a Solution I think the Nd can be only...
  8. L

    Automotive What happens when a turbocharger hits it's stonewall point?

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  9. R

    Magnitude of electric field at point A using components

    Homework Statement https://imgur.com/gallery/YwCap In side are image of figure, and questions.Homework Equations E = kq/r^2 The Attempt at a Solution So I have an electric field where the y compontents cancel. I have 2Ecos(∂) = E (Electric field at point A) - 2 because there is a top and...
  10. P

    Turkey Point nuclear powerplant and Irma?

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  11. B

    Interactions between a dipole and a point charge

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  12. M

    Two object leave the same point with different speeds

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  13. M

    Projectile Motion -- position and the highest point

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  14. B

    Force on a 3rd point charge due to 2 other point charges

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  15. E

    Angle between a Point on a Ellipse and its Center

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  16. Eclair_de_XII

    Force on a test charge due to two point charges?

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  17. E

    A Transformation of the neighborhood of a branch point

    Hi all, I was trying the understand theory behind Fourier and Laplace Transform (especially in the context of control theory) by reading the book "Complex Variables and the Laplace Transform for Engineers" written by "Wilbur R. LePage". In section 6-10 of the book the author touches on the...
  18. K

    Line passing through a point and normal to a curve

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  19. K

    Dynamics of a point mass in circular motion

    Homework Statement Dear All, I'm having a hard time solving the following problem: A point of mass is moving on a circular plane (Oxy), where the circle's formula is: The force acting on mass "m" is defined as: We're looking for velocity of point "m" in position (1,1) =V1, and in position...
  20. Enigman

    Looking for a low boiling point solvent for MAPI precursors

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  21. karush

    MHB 231.12.3.63 Determine the smallest distance between point and line

    $\tiny{231.12.3.63}$ $\textsf{Determine the smallest distance between point $P(1,1,1)$}$ $\textsf{ and the line $L$ through the origin}$ $\textsf{ $L$ has the direction $\langle -4,-5,8 \rangle$}$ $\textit{ok I know the formula to use basically is}$ \begin{align*}\displaystyle...
  22. A

    MHB Finding missing point of a vector when it is perpendicular to a line

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  23. B

    What is the pressure at point B in a moving liquid with density ρ?

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  24. karush

    MHB 231.12.3.65 Determine the smallest distance between a point and a line

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  25. Alexanddros81

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  26. S

    Magnetic Field of a Rectangular Loop at Point P

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  27. Pushoam

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  28. C

    Field pattern -- Which can be produced by 2 point charges?

    Homework Statement Homework EquationsThe Attempt at a Solution why not B?
  29. binbagsss

    Wick theorem proof 4 point correlator 2 different fields

    1. Homework Statement Attached: Homework Equations I've just changed the notation a tad to make things quicker for me : ##\phi_1=\phi_1(x_1)## and ##\Phi_2=\phi_2(x_2)## : denotes normal product. i.e annhilator operators are on the RHS, so acting on a vacuum state will give zero. I can...
  30. H

    Shortest distance between a line and a point?

    Homework Statement find the shortest distance from (0,0) to the line passing A(2,3) and B(3,5) Homework Equations ## \frac{y-y1}{y2-y1} = \frac{x-x1}{x2-x1} ## y-y1 = m (x-x1) m1 * m2 = -1 (m1 perpendicular to m2) The Attempt at a Solution line passing A and B points ## \frac{y-3}{5-3} ## =...
  31. J

    Operating Point Calculation for a Centrifugal Pump in a Process System

    Homework Statement A centrifugal pump has the following pressure – capacity characteristics: It is planned to use this for a process having the following system characteristic: (a) Determine the operating point for this pump with this system. (b) The actual flowrate required by the...
  32. S

    Time period of small oscillations of the point dipole

    Homework Statement In an infinite flat layer of thickness 2d, volume charge density is given according to the law: ρ=(ρ°)(x)/d and (-d≤x≤d). Here, x is the axis perpendicular to the plane. In the layer, there is a thin channel in which a point dipole of mass m and dipole moment p is placed...
  33. jlmccart03

    Velocity of a particle kicked into four point charge square

    Homework Statement Consider the arrangment of charges (fixed in place) shown in the figure. The square has side length d. (Figure 1) Now suppose the particle with charge q is released. It is "kicked" so that it's initial speed is v. After an unspecified trajectory, it is observed that the...
  34. M

    MHB Rotation around an arbitrary point

    Hey! :o I want to rotate the point $(10, 11)$ with rotation angle $\frac{\pi}{3}$ around the point $P=(-1,-1)$. I have done the following: We translate about $-\vec{OP}$: \begin{equation*}P'=(-1\mid -1)-(-1\mid -1)=(0\mid 0)\end{equation*} We rotate around the origin...
  35. L

    MHB Find XYZ for Tip of Vector Given Info on 2 Other Vectors w/ Tails at Same Point

    I have posted this in University linear algebra, but it is possible there is a simple answer for this and the the problem belongs in some other forum. I apologize if that is the case. I am starting with 3 points in 3 space, along with the centroid of the full data set. The data is in principle...
  36. Y

    MHB Distance between point and line

    Hello all, I need your assistance with the following: Find the equation of the line that goes through the origin (0,0) if it is known that the sum of distances of the line from A(2,1) and B(1,4) is equal to \[\sqrt{8}\], and it is also known that the line is between the points. The formula I...
  37. chopnhack

    Two point charges repelling, stretching a spring

    Homework Statement Two spherical point charges each carrying a charge of 40 mC are attached to the two ends of a spring of length 20 cm. If its spring constant is 120 Nm-1, what is the length of the spring when the charges are in equilibrium? Homework Equations 1) F = k*(q^2)/r^2 where k is...
  38. S

    I Two point correlation function in Peskin book

    Hello! I am reading Peskin's book on QFT and I reached a part (in chapter 4) where he is analyzing the two-point correlation function for ##\phi^4## theory. At a point he wants to find the evolution in time of ##\phi##, under this Hamiltonian (which is basically the Klein-Gordon - ##H_0## - one...
  39. M

    MHB Cruiser & Destroyer: Finding the Closest Point

    a cruiser is 12 km due west of a destroyer . the cruiser is traveling in a direction 60 degrees N of E at 30 km hr^-1 and the destroyer is traveling at 15 km hr^-1. find the direction the destroyer must travel in order to get as close as possible to the cruiser there is complicating way to do...
  40. M

    Scalar Moment around a point due to a force

    Homework Statement In two dimensions, the moment of a force can be calculated using the scalar method, MO=Fd, where F is the magnitude of the force and d is the perpendicular distance from the line of force to the point where the moment is being considered. Using the scalar method, calculate...
  41. chopnhack

    Point charges in a equilateral triangle - typo in solution?

    Homework Statement Three point charges each carrying a charge of 11.0 µC are located at the corners of an equilateral triangle of side 15.0 cm. Calculate the magnitude and direction of the force on each charge. Homework Equations k = 9.0x109NM2C-2 F = k⋅(Q1⋅Q2)/r2 The Attempt at a Solution...
  42. S

    Freezing point of an aqueous solution

    hi i am trying to figure out the way to calculate the freezing point of an aqueous solution which have 5 different components. if someone can refer me to an example or give me and example it will be great thanks in advance sharon
  43. MrsTesla

    Northernmost Point of a Route: Finding Distance and Latitude from North Pole

    Homework Statement Find the distance between Helsinki and Seattle along the shortest route. Where is the northermost point of the route, and what is its distance from the North Pole? The longitude of Helsinki is 25ºE and latitude 60º; the longitude of Seattle is 122ºW and latitude 48º. Assume...
  44. J

    I Reference point of geocentric lunar latitude?

    I'm attempting to use an algorithm translated from Jean Meeus: Astronomical Algorithms. The algorithm in question finds a geocentric position of the moon given a certain day. I have been able to find the geocentric longitude of the moon, but I don't know what this longitude is in reference to...
  45. joerylee palmerola

    Electric field due to a point charges

    Suppose a charge q is placed at point x=0, y=0. A second charge q is placed at point x=8.0m, y=0. What charge must be placed at the point x=4.0m, y=0 in order that the field at the point x=4.0m, y=3.0m be zero?
  46. H

    DG Connection: Estimating Voltage Rise at Point of Common Coupling (PCC)

    Hi! According to the book "Renewable Energy on Power Systems" by Freris & Infield, the voltage rise due to injection of power in pcc can be estimated from the Thevenin equivalent representing the network "upstream" pcc (Figure 1). The Thevenin voltage can be taken as the nominal voltage in the...
  47. SirLollington

    Collimating a laser beam with a fixed focal point?

    Hey, Not sure if this is the correct sub-forum to post this question. I'm still kinda new here, so sorry if I got it wrong :smile: I have a laser module with a fixed focal point of 16 mm and I'm trying to collimate that light into a beam. The point of focused light is at most a quarter...
  48. F

    Find electric Field at a point A

    Hi Guys, I've been learning electric field, and i want to ask about this question.EF net = EF1 + EF2 my EF1 = 9 x 109 * 4 x 10-8 / (0.6)2 = 1 x 103 (From Q1) EF2 = 9 x 109 * 2 x 10-8 / (0.3)2 = 2 x 103 (From Q2) then EFnet = (2+1) x 103 = 3 x 103 and what i get from key answer is 2.2 x 103...
  49. Decimal

    Magnetic field from a wire at a point

    Homework Statement Picture of the problem: I first need to calculate the magnetic field in point P caused by the piece of wire at z = R (so the top wire parallel to the y-axis). Homework Equations [/B] Biot-Savart law for magnetic fields: ##\vec {dB} = \frac {μ0*I} {4*π} * \frac {\vec {dl}...
  50. C

    MHB Two tangent at the same point of a function

    it is possible to have two different tangents at the same point of a function?
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