Point Definition and 1000 Threads

  1. evinda

    MHB Where Do the Diagonals of a Parallelogram Intersect?

    Hello! (Wave) Suppose that a parallelogram $ABCD$ has vertices $A=(0,0)$ and $B=(1,0)$. In terms of $C=(x,y)$, find the position of $D$ and where the two diagonals will intersect. Then we will have something like that: How can we find the coordinates of $M$, i.e. the point at which the two...
  2. evinda

    MHB How Do Cylindrical and Spherical Coordinates Represent the Same Point?

    Hello! Suppose that a point has cylindrical coordinates $(r, \theta, z)$ where $r$ is not zero. Describe all other cylindrical coordinates of that point. Suppose $(R, \theta_1, \phi)$ and $(R, \theta_2, \phi)$ are two representations of the same point in spherical coordinates. Is it true that...
  3. BubblesAreUs

    Python Finding Epsilon & Smallest Floating Point - Python

    I'm finding it difficult to find the exact value of epsilon on python? Moreover, I am also supposed to find the smallest floating point number as well. Wikipedia tells me that the machine epsilon is 2−52 ≈ 2.22e-16 for 64-bit IEEE 754 - 2008? Is this the exact value on Python? Outside of...
  4. H

    Isolated Point Charge and Work?

    This is a really abstract question, and I'm absolutely clueless on how to approach it. I know W= F*d, where F=force and d=distance, as well as W= PEa-PEb. The question reads: The diagram shows an isolated point charge. Marked are four paths (A, B, C, and D) from a point (P1) to point (P2). The...
  5. J

    I Average number of times a random walk passes a point

    Hi, I'm trying to work out how many time a particle going on a random walk starting at the origin would pass a particular point or points for a given total number of steps. I've simulated the problem and get approximately the same answer every time, however I'm struggling to know where to even...
  6. B

    MHB Finding equation normal to a plane and certain point

    For the following question I am given a plane: x + 2y + 3z = 12. I want to find the equation of a line normal to the plane and going through the point (4,6,8). I am trying to use the formula N . (r - r0) = 0 however seem to be getting the incorrect answer :(
  7. G

    MHB Finding the Position Vector of Point $B$ on a Line Segment Between $P$ and $Q$

    Let $P = (1,2,-1)$ and $Q = (3,1,0)$. A point $B$ lies on the line segment between $P$ and $Q$. Given that its distance from $P$ is twice its distance from $Q$. Find the position vector of $B$.
  8. P

    What is the Intensity of Seidel Point?

    Hello I have to prove that the intensity of seidel point is equal to ##I_{sp}=\frac{8}{\pi^2} I_o## I didn't get any other information only that there is an integration in this prove. Hope you can help me. It is enough for me if you only give me link or the name of this prove.
  9. A

    Reference point ground vs Earth-ground

    Homework Statement I have seen Earth and ground used interchangeably. However, there appears to be some distinction with regards to reference point ground and Earth ground. My textbook used an example of a loaded voltage divider and examined how the voltage across certain resistors can be...
  10. B

    Proof that disk of charge = point charge when very far?

    Homework Statement Take the expression 21.11 (pictured below, specifically the bottom one) for the electric field above the center of a uniformly charged disk with radius R and surface charge density σ, and show that when one is very far from the disk, the field decreases with the same square...
  11. F

    Integration to find Electric Field at a point P -- dQ or dq?

    Hey everyone, So I've been learning about electric fields and all that good stuff. So now the question arises, what is the electric field at a point P away from an object (say a rod or a ring) at a distance D away? So we know E=Kq/r2 or E=KQ/r2 . The difference between q and Q: q the charge for...
  12. E

    Magnetic Field due to a Point Charge

    Hi. I'm currently learning about magnetism, however the course I'm in doesn't combine special relativity with E&M so I just wanted to do some personal exploring. The magnetic field for a point charge is proportional to V1 x R of the charge. Then, the magnetic force is proportional to V2 x B...
  13. K

    What results can be found from point set topology?

    Hello! I'm currently teaching an advanced course in mathematics at high school. The first half treats discrete mathematics, e.g. combinatorics, set theory for finite sets, and some parts of number theory. Next year I would like to change some of the subjects in the course. My question is: Are...
  14. J

    Velocity of a point charge from work done

    Homework Statement If a charge of +2 µC and mass 2 g is taken to (0,0,4) in the presence of an electric field due to a ring {R : x2 + y2 = 25,z = 0} of uniform charge density ρL = +3µ C/m, and then released, find the maximum velocity it gains. Given in the problem: You solve the equation 1/2...
  15. J

    Work done by moving a point charge

    Homework Statement [/B] Three point charges each of 4 µC are situated at the three corners of an equilateral triangle of side 4 m. Find the work done in moving one of them to a point mid-way between the other two. Solution: The Potential difference VAB between two points A and B is the work...
  16. J

    Amplitude at the point of interference

    Homework Statement [/B] Consider 2 radio antennas placed on a 2 dimensional grid at points x1 = (300,0) and x2 = (-300, 0). If the antennas are out of phase such that ϕ2-ϕ1 = π/4 and both are emitting waves of frequency 2.59 MHz. What will the amplitude of the resultant wave be at the point...
  17. henrco

    Find the electric force on a point charge

    Homework Statement A point charge q1 = 4.40 μC is at the origin and a point charge q2 = 6.00 μC is on the x axis at x = 2.49 m. i) Find the electric force on charge q2 ii) Find the electric force on charge q1 Homework Equations Coulomb's law F = k (q1q2)/d^2 The Attempt at a Solution Part...
  18. E

    Determining an error due to non point like detector

    Homework Statement Recently I have conducted an experiment using a gamma source (22Na) and a scintillation detector (NaI), at the start of the experiment one of the desired outcomes was to see that the intensity of the source fell off as 1/r^2. Seeing as the detector is not point like (I am...
  19. J

    How does a virtual particle becomes a point interaction?

    If you want to show that a propagator of a heavy particle reduces to a point interaction at distances large compared to the inverse mass of the particle by Taylor expanding the propagator (for simplicity take 1-dimension): $$G(x)=\int^\infty_{-\infty} \frac{dk}{2\pi} \frac{e^{-ikx}}{k^2+M^2}=...
  20. M

    Ending point for initial condition theories

    I am not a scientist, but as a hobby I am summarizing different initial condition theories, specifically, eternal inflation, LGC, cyclic, and bounce theories. I need a completion time ATB where all theories produce an identical plasma. The plasma then enters the big bang process of expansion...
  21. G

    Finding E-field at a point away from a line charge

    Homework Statement A line charge with a uniform linear charge density Lambda lies along the x-axis and extends from -∞ to 0. Determine the X-component, and Y-component of the E-field at a point P, a distance 'a' from the origin on the positive y-axis. Homework Equations dE= (k*dq/r^2)* r(hat)...
  22. 6

    2 photons, same starting point/time, same end point

    How would 2 photons with the same starting point& time and same end point view each other's positions, time and distance from start to end point. I recognize this is likely a bad question, so any input would be helpful.
  23. gracy

    Velocity of charge at the center thrown from far away point

    here from time 0:53 to 0:58 velocity at center would be more than or approximately equal to zero .I want to ask why approximately zero why not zero?
  24. K

    Find Focal Length of Diverging Lens | Physics Homework Help

    Homework Statement When an object is placed at the proper distance to the left of a converging lens, the image is focused on a screen 30.0 cm to the right of the lens. A diverging lens is now placed 15.0 cm to the right of the converging lens, and it is found that the screen must be moved 19.2...
  25. S

    MHB Find the equation of the plane given a point and two planes

    I've done a question similar to this, however this one has no complete equations i can solve for. Determine the equation of the plane that passes through (1,3,8) and is perpendicular to the line of intersection of the planes 3x−2z+1=0 and 4x+3y+7=0. I know to take the cross product of the two...
  26. O

    Potential at a point due to conducting sphere and sheet

    There's this question, A conducting sphere of radius R and charge Q is placed near a uniformly charged non conducting infinitely large thin plate having surface charge density σ. The potential at point A on sphere due to charge on sphere is? I have uploaded the picture. Now I know the net field...
  27. woprxcpe1704tks

    Force on point charge caused by another point charge.

    Homework Statement Consider two equal point charges q, separated by a distance 2a. Construct the plane equidistant from the two charges. By integrating Maxwell’s stress tensor over this plane, determine the force of one charge on the other. I have the full solution, but I'm confused on one...
  28. O

    What's the equivalent resistance between point A and B?

    Simple as that, I've uploaded the image. I don't really care about the exact value, I would prefer just to know the method. So how would I find the equivalent resistance between A and B? Note the component in the middle is a constant current source.
  29. L

    Inertia tensor combination point mass-sphere

    Homework Statement hello, i want to calculate the inertia tensor of the combination of a point mass and a sphere in the object's frame, the center of mass is at the origin. The point mass remains at the surface of the phere The sphere is uniform, radius r and mass M, and the point mass has mass...
  30. Muskovite

    Consider the motion of a point mass m in the potential V(r)

    Homework Statement Consider the motion of a point mass m in the potential V(r)=-k/r , k>0 Show that there is a solution x(t) of the equations of motion which is a circular motion with constant circular frequency ω. Determine the relation between ω and the radius of the circular motion. Show...
  31. awholenumber

    A few more questions about fixed point iteration ....?

    first of all i simply don't want to give up learning numerical methods ... i am trying to follow fixed point iteration method from this link ... http://www.ce.utexas.edu/prof/mckinney/ce311k/Overheads/14-NonlinearEquations_1_FixedPoint.pdf fixed point iteration can be used to solve...
  32. A

    At what point along the x axis is the electric field zero?

    Hello, I've been trying to answering this question but my answer is always wrong. Two point charges, -9.10 μC and 21.29 μC, are placed at x = 0 cm and x = 8.00 cm, respectively. (a) At what point along the x-axis is the electric field zero? What i did: i figured that the point should be on the...
  33. Domenico94

    Understanding Genetic Inheritance: A Two or Three Point Test Example

    Hi everyone. Can someone please explain me how a two or three points test can be made, in the field of genetics? I've read of it in many books, but I'm looking for an explanation as clear as possible. Thanks in advance :)
  34. S

    From the point of view of the speed of light

    It has been made clear to me that any velocity can be seen as rest mass, meaning that if I observe someone else experiencing time more slowly than me due to general relativity, so long as they do not change velocities, they will see me as experiencing time more slowly than them. I have also...
  35. C

    Electric field of a dipole at an offset point

    Note: Post edited by moderator: 1. Homework Statement Homework Equations I can't use voltage, nor polar coordinates (got to stick with cartesian). Cartesian vector form of Coulomb's Law The Attempt at a Solution
  36. Destroxia

    Find parametric equation at point, and parallel to planes?

    Homework Statement Find parametric equation of the line through the point ##(4,0,-4)## that is parallel to the planes ##x-8y+7z=0## and ##4x+3y-z+4=0##. Homework Equations ## \vec r = \vec r_0 + t\vec v ## (for orthogonal vectors) ## v \bullet w = 0 ##[/B] The Attempt at a Solution So I...
  37. T

    MHB Starting with center of thrust to find amount of force on each point?

    I'm playing a game, From the Depths, that let's you build your own helicopter blades (and put them on ships that you build) and program in LUA. I did some searching and found: Calculating the Center of Thrust on Multirotors | Flite Test Currently, there is no way to tell how much lift a given...
  38. T

    Which Compound Has Highest Boiling Point?

    Homework Statement Of the following compounds, which has the highest boiling point? (A) CH3—CH3(B) CH3—CH2OH(C) CH3—COOH(D) CH3—COH(E) H2S Homework Equations - The Attempt at a Solution Chose C because is more polar with the 2 oxygens, however, the answer has conflicting answer. It...
  39. S

    Intermolecular forces and boiling point

    I've come to understand that intermolecular forces cause the boiling point of hydrochloric acid solutions below 20% to be higher than the boiling point of water. I also understand that dissolving hcl in water is an exothermic reaction. But, what about those intermolecular forces. I assume they...
  40. R

    Closest line from a point to a curve in R^2

    Given a parametrized curve ##X(t):I\to\mathbb{R}^2## I am trying to show given a fixed point ##p##, and the closest point on ##X## to ##p##, ##X(t_0)##, the line between the point and the curve is perpendicular to the curve. My only idea so far is to show that...
  41. J

    A check: shortest distance from point to line

    We want to know the shortest distance from the point P to the line (see figure 1). As far as I know it is given by the length of the segment perpendicular to the line that joins the line to the point. Can you check this argument I give is correct? Part A. First let us draw in the segment from...
  42. S

    What is the point of these rows?

    I have a book SQL Antipatterns that shows how to use tables to represent a relationship like 1 / \ 2 3 / \ \ 4 5 6 / 7 with a table like CommentPaths ============================ ancestor_id | descendant_id...
  43. T

    How do solute particles increase boiling point?

    The question is: Which solution listed below is going to have the highest boiling point? A. 1.5 m NaCl B. 1.5 m AgCl C. 2.0 m C6H12O6 D. 2.0 m CaCl2 E. 1.0 m Al2(SO4)3 I chose D (which was right) because in a solution, the more solute particles there is the higher the boiling point (this is...
  44. E

    Calculating to mass of a water column above a specific point

    Part D. I looked up the answer and input it already, which is why it says correct, but i am beyond stumped. No idea how to do this. I know the pressure at the dotted lines are equal and that pressure=force/area. I also know the pressure at an area is equal to whatever is above it so the pressure...
  45. E

    Does Propanoic Acid Have a Lower Boiling Point Than n-Butyl Alcohol?

    Homework Statement State true or false: The boiling point of propanoic acid is less than that of n-butyl alcohol, an alcohol of comparable molecular weight. Homework EquationsThe Attempt at a Solution Is this just a question where you either know it or don't OR is there some argument based off...
  46. evinda

    MHB How do we deduce that there is such a point?

    Hello! (Wave) Let $k(x)$ and $g(x)$ be continuous functions such that $k(x)>0, 1 \leq g(x) \leq 10$. Show that the problem $ y'(x)=g(x)-k(x)y^2(x), y(0)=0(\star) $ has a global solution. We firtsly show that if the solution exists then for all $x>0$ it holds $0< y(x) \leq 10 x$. Indeed ...
  47. karush

    MHB A particle traveling in a strainght line passes a fixed point O

    so if $a\left(t\right)=p+qt$ then $v\left(t\right)=\int a\left(t\right) dt = pt+\frac{q {t}^{2}}{2}+C$ if $v=3.5$ when $t=2$ then $1.75=p+q$ if so, now what? the answers are $4, -3; 4m$
  48. NihalRi

    The point of the Euler-Lagrange equation?

    When trying to come up with the geodesic equation for a sphere I came across this equation. My question, is this equation just a short cut so we don't have to integrate and differentiate with two variables. Here is the equation...
  49. A

    Can we apply Friss equation to find field strength at the receiving point....

    Can we apply friss equation to find field strength at the receiving point for space wave propagation?
  50. stvrbbns

    2D - What is the next point given this info.

    In a two-dimensional environment: Given: a starting point (x1,y1) an initial velocity (speed and 2D heading/direction) a constant rate of turning (yaw, since there is no roll or pitch in only two dimensions) a constant acceleration of the object from itself (not like gravity where the direction...
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