Point Definition and 1000 Threads

Homework Statement In order to pull out the nail at B, the force F exerted on the handle of the hammer must produce a clockwise moment of 590 lb⋅in about point A.(Figure 1) Determine the required magnitude of force F. Homework EquationsThe Attempt at a Solution M=590lb*in -590=...

Homework Statement The towline exerts a force of P = 5.8 kN at the end of the 8-m-long crane boom. If θ = 30∘ determine the placement x of the hook at B so that this force creates a maximum moment about point O. Homework EquationsThe Attempt at a Solution M(max)= 8(5800) = 4.64kN*m My...

Homework Statement As a stunt coordinator with a background in physics, you have been asked to determine whether Man can make it across the river and whether the rope will hold his weight. Man is rather small, with a mass of only about 48.7 kg, including his equipment. The crossing distance is...

Homework Statement [/B] Determine the moment about point B of each of the three forces acting on the beam. Homework Equations M = F*d⊥ The Attempt at a Solution I went and found the components for each of the forces. Please double check it if I did them right: F1 : Fx = 0 Fy = 375 lb F2: Fx...

Homework Statement A long wire (X) carrying a current of 30 A is placed parallel to, and 3.0 cm away from, a similar wire (Y) carrying a current of 6.0 A. What is the flux density midway between the wires: (a) when the currents are in the same direction, (b) when they are in opposite...

Andy Resnick submitted a new PF Insights post Digital Camera Buyer's Guide: Compact Point and Shoot Continue reading the Original PF Insights Post.

Homework Statement Find the interaction energy ( ##\epsilon_0 \int \vec{E_1}\cdot\vec{E_2}d\tau##) for two point charges, ##q_1## and ##q_2##, a distance ##a## apart. [Hint: put ##q_1## at the origin and ##q_2## on the z axis; use spherical coordinates, and do the ##r## integral first.]Homework...

Homework Statement The diagram shows a section of a curtain track in a vertical plane. The curved section, CDE, forms a circular arc of radius of curvature 0.75 m and the point D is 0.25 m higher than B. A ball-bearing of mass 0.060 kg is released from A, which is 0.50 m higher than B. Assume...

I posted this before but I think it was in the wrong, place, so sorry for the duplicate :O I'm trying to work through some equations in the paper 'Gravitational Radiation and the Motion of Two Point Masses' (Peters, 1964) but I can't get out the right values 1. Homework Statement For a binary...

I'm trying to work through some equations in the paper 'Gravitational Radiation and the Motion of Two Point Masses' (Peters, 1964) but I can't get out the right values 1. Homework Statement For a binary star system with each mass = 1 solar mass, the equations give the results: Separation ~ 10...

Does a limit exist on a graph at (-1,0) if the point is solid, and has a right sided limit, but there is nothing left of the point? I understand that if the left sided limit and the right sided limit are different then it doesn't exist, but on my graph it shows a line coming from the right...

A portion of a sketch drawn by a student to obtain the location of a point P which lies at a distance of 3cm from the given straight line AB and 5cm from the point A, is shown in the figure. Complete the sketch and mark the location of the point P. This is is already included. And the...

Hello. Here is my problem: I want to mount 2 solar panels on a horizontal 10 foot bar. (panels are 5' and 20-40/lbs each - so 80lbs) is there a formula i can use on each material option to figure out what material to use for the 10 foot bar (what won't break under the weight of the panels or...

Homework Statement Show that the path line of a particle at point x currently, and point ξ at time τ is given by ξ(τ) = x + (τ-t)Lx Homework Equations Pathline is solution to dx/dt = u x(t)|t=τ = X L is the velocity gradient and is a 2nd order tensor Lij = dui/dxj The Attempt at a...

I'm studying for my physics exam and there is a figure on the book physics for scientists and engineers 4th edition by giancoli that i just don't understand. I know that the electric field of a negative charge points toward it and the electric field of a positive charge points away from it Also...

Homework Statement A point source isotropically emitting 10^8 fast nuetrons per second falls out of its shield onto a railroad platform 3 m horizontally from the track. A train goes by at 60 mph. Ignoring scattering and attenuation, what is the fluence of nuetrons that would strike a passenger...

So I have solved the following problem: Consider two points located at ##\vec{r}_1## and ##\vec{r}_2##, separated by distance ##r = |\vec{r}_1 - \vec{r}_2|##. Find a vector ##\vec{A}## from the origin to a point on the line between ##\vec{r}_1## and at ##\vec{r}_2## at a distance ##xr## from the...

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##...

Homework Statement What is the distance from the point P to the plane S? Homework Equations ## S = \left \{ r_{0} + s(u_{1},u_{2},u_{3})+t(v_{1},v_{2},v_{3}) | s,t \in \mathbb{R} \right \} ## The Attempt at a Solution [/B] I found an expression for the general distance between point P and a...

I have been reading about and contemplating the early stages of star formation lately. An interstellar cloud collapses under it's own gravity to form a star. There is much data about what could trigger it, and what happens when the gas heats up or starts fusing. However, i couldn't find...

Hi all! I have a question regarding the principal difference between QFT and string theory according to popular accounts. It is said that QFT deals with point particles leading to the well-known infinities in calculating the transition amplitudes whereas in string theory the interaction is...

Not sure whether this is an intro physics or intro calculus/related rates problem. 1. Homework Statement Suppose a point P lies at (x,y)=(0,1) meters. A car is traveling at 30 meters/second along the x-axis towards +∞. Define r to be the distance between P and the car at any time t. I...

Because gravity travels at the speed of light in GR, there seem to be a few possible places where gravity could pull you towards if dealing with some massive object in some orbit, which one of these is predicted?1. To the position where you see the object (the place where the object used to be)...

Homework Statement [/B] I was doing http://stao.ca/VLresources/sci-tie-data/lessons/1400_1499/DivergingLensExperimentDeta.pdf experiment. Let's look at this image: Suppose we get the imaginary object at dv by convergence lens. And this object is like a real object for the concave lens. Then...

Homework Statement I have the function: f(x,y)=x-y+2x^3/(x^2+y^2) when (x,y) is not equal to (0,0). Otherwise, f(x,y)=0. I need to find the partial derivatives at (0,0). With the use of the definition of the partial derivative as a limit, I get df/dx(0,0)=3 and df/dy(0,0)=-1. However, my...

Homework Statement Hi, The question is " Three point charges (q,−2q,q) are located in a straight line with separation a and with the middle charge (−2q) at the origin of a grounded conducting spherical shell of radius b ..." I have found a solution for this problem but there is one step that...

"Understand that, for a point outside a uniform sphere, the mass of the sphere can be considered a point mass." This is one of the "learning outcomes" in the A level Course. Here are my questions related to it. 1.) What is meant by point masses? (A definition will do) 2.) Why do we consider...

Quoted data for cis and trans 1,2 dichloroethenes shows cis has higher density but lower melting point than trans. How can this be explained? Packing arguments are clearly unable to rationalise these observations. Other 1,2 disubstituted ethenes show similar pattern. Thank you.

Homework Statement [/B] A square plate of side-length L, charged with uniform surface charge density η. It is centred at x = y = z = 0 and orientated in the z = 0 plane. The task is to determine the z-component of the electric field at the point r(x, y, z) = r(x, 0, d), offset along the...

I used to know this back when i worked with Flash animation, but I'm working on a 3D printer now and I've forgotten, when you have a set of teeth, on a linear shaft and a gear, do you base the unrolling of the gear, for the spacing, on the inside of the teeth, the outside of the teeth, or the...

whats the turning point of (1-lnx)², x>2 is it a minimum or maximum. can someone help me

Homework Statement A point source of light (wavelength \lambda = 600 \, \text{nm} ) is located a distance x = 10\,\text{m} away from an opaque screen with a small circular hole of radius b. A very small photodiode is moved on an axis from very far away toward the screen. The first...

Homework Statement Let be ##f \in C^{1}(\mathbb{R}^{n}, \mathbb{R}^{n})## and ##a \in \mathbb{R}^{n}## with ##f(a) = a##. I'm looking for a suffisent and necessar condition on f that for all ##(x_{n})## define by ##f(x_{n}) = x_{n+1}##, then ##(x_{n})## converge. Homework Equations ##f(a) =...

Hello, First of all, this question does stem from graduate work, but it seems far too simple to tag "advanced". I am looking to write some code to simulate the force from a railgun. The first step in doing this (from a tutorial I found) is to find the magnetic field at any point within the...

Homework Statement Find what x is I don't understand what to do with (3x-23). Homework Equations Angles centered at a point: a+b+c+d=360 https://drtayeb.files.wordpress.com/2011/03/igcse-math-extended.pdf (here is a pdf of the textbook, Exercise 4A, 3i.)[/B]The Attempt at a Solution...

GH is a straight line. the coordinates of G are (-2,8) the midpoint of GH is (5,-3) work out the coordinates of H

1. The problem sttatement, all variables and given/known data i don't understand the moment FDC(sin18.43)(9) , I think it's wrong.. http://imgur.com/a/qPdqf Homework EquationsThe Attempt at a Solution I think it should be FDC(cos18.43)(3), am i right? the r is the perpedicular distance from D...

Homework Statement for moment about C, the author gave [-F_(FE)](5) +3.2(4) +6(5) = 0 i don't understand the working...Why there are moment 3.2(4) and also moment 6(5)? Homework EquationsThe Attempt at a Solution for moment 3.2(4) , it's centered at F, so ,it's not moment about C ,am i...

My book states that "irradiance at a point on the outer sphere is less than irradiance at a point on the inner sphere." The formula is simple, it's flux/area. So in case of a sphere its flux/4π*r^2. But my question is what exactly does this formula give? does it give the total flux that...

Why all liquids vaporize on boiling point instead of the temperature gradually increasing along with vapor pressure and more liquid atoms evaporating? Does it have anything to do with formation of vapor bubbles?

I am struggling with this question, it would be easy enough if the triangle was equilateral but that is not necessarily the case. Let (ha, hb, hc) be heights in the triangle ABC, and let Z be a point inside the triangle. Further to this, consider the points P, Q, R on the sides AB, BC and AC...

I am trying to create a function of A and x which has the following properties. A is a scaling parameter that determines the shape of the function. I write the function below in f(A,x) form 1) f(A,1)=1 always 2) For all x>1, 0<f ' (x)<1 3) As A approaches some upper bound (which could be...

Say there is a point particle attached to a rope of radius r. It spins with angular velocity w. As a result, the force needed to keep this particle in circular motion is: F = mv2/r However, now say I have some irregular shaped object, with say some constant surface density for simplicity. It...

Hi,I have been stuck on this problem The midpoints of the sides AB and AC of the triangle ABC are P and Q respectively. BQ produced and the straight line through A drawn parallel to PQ meet at R. Draw a figure with this information marked on it and prove that, area of ABCR = 8 x area of APQ. I...

I'm trying to prepare to read The Large Scale Structure Of Space-time by Hawking and Ellis. I've been reading a General Topology textbook since the authors say "While we expect that most of our readers will have some acquaintance with General Relativity, we have endeavored to write this book so...

By classical E&M I mean the general basics. I understand that even classical EM has clear relativistic undertones, but is anything taught classically actually wrong under the context of relativistic EM? For example, does Faraday's law continue to hold etc. I know this is kind of a broad...

I am currently an undergrad studying physics and am doing research on PPLN and nonlinear optics. I have a basic understanding of the math involved with my research, but would like to know more on nonlinear optics and why these materials behave the way they do. I am currently reading...

Homework Statement What is the gravitational field strength at a point 6.38x106 m above the Earth's surface? Homework Equations The Attempt at a Solution Ok so I plug in all the known variables. G= 6.67x10-11. M= 5.98x1024. r= 6.38x106 and so I multiply that by 2 because the given point is...

Homework Statement This is more of a general question, but a simple example would be find the force on a test charge q at the center of a ring of charge with a total charge Q and a charge distribution given as λ(θ) =ksin(θ) where θ is measured clockwise with respect to the positive x-axis. The...

Hi (I hope this is the right place to post this - sorry if it's not) Say I have a line (in the graphic is shown a 10mm but it could be any length) and it rotates around a point at one end. What is the formula to get the length along the x-axis directly under the other end of the line. In the...