Normal Definition and 1000 Threads

Why are so many phenomena well described by the normal distribution? For example: the height of 18 year old males in Sweden, the weight of apples on a particular tree, the volume of coke cans (supposed to be 33 cl), etc. etc. are all well described by the normal distribution. How come? A...

In the past I used to understand it in some kind of way. But it doesn't make a lot of sense sometimes. In high school, we usually take examples where the object is placed in an incline and the Normal force is equal to mg cos theta where theta is the angle of the incline. It should equal to that...

Homework Statement Hi everybody! I'm really struggling with those exercises from my special relativity class, and I'd like to know what you think about that one because I come up with a strange result: The motion of a point mass in a plane is given by: x = a cos(ωt), y = b sin(ωt) Calculate...

Hello everyone, This has bothered me for sometime now. Ok Pulmonary embolism , now decreased perfusion into a part of lung. No blood available for oxygen from lung to diffuse into. Blood has decreased oxygen. That is fine but since no blood is reaching the lungs, the carbon dioxide should also...

Homework Statement I have to determine the frequencies of the normal modes of oscillation for the system I've uploaded.Homework Equations [/B] I determined the following differential equations for the coupled system: \ddot{x_A}+2(\omega_0^2+\tilde{\omega_0}^2)x_A-\omega_0^2x_B = 0...

Hi everybody! I'm currently learning special relativity, and I'm going through the chapter of tangent, normal and binormal vectors. In my teacher's script, the definition of the normal vector eN says: \vec{e_N} = \frac{d}{ds} \vec{e_T} \cdot \frac{1}{\mid \frac{d}{ds} \cdot \vec{e_T} \mid} =...

Let the surface $S \subset \mathbb{R}^3$ be the graph of the function $f: \mathbb{R}^2 \to \mathbb{R}$, $f(x,y)= \sqrt{x^2+y^2+1}$. Let $U$ be the finite region of $S$ below the plane $z = 2$ and let $D$ be the finite region of the plane $z = 2$ for which $x^2 + y^2 \le 3$. Let $n_U (x, y, z)$...

Hello everyone, I have a question. I'm not sure if it is trivial. Does anyone have ideas of finding a matrix ##A\in M_n(\mathbb{C})##, where ##A## is normal but not self-adjoint, that is, ##A^*A=AA^*## but ##A\neq A^*?##

I know that orbital angular momentum is quantized. If the potential energy is developed because of the external magnetic field applying a torque on the magnetic dipole, then from the dot product of the dipole moment and magnetic field we have a cosine term, shouldn't this give rise to all the...

Homework Statement Draw the combinatorial circuit corresponding to the disjunctive normal form. Homework Equations DNF of f(x,y,z)=xyz+Not(xy)z The Attempt at a Solution f(x,y,z)=xyz+not(xy)z =z(xy+not(xy)) Wouldn't the xy and not xy cancel out? That's my current problem with this...

Homework Statement A jet of water , 50mm diameter , with a velocity of 18m/s , strikes a flat plate inclined at 25 degree to the axis of jet as shown in figure, Determine the normal force , P exerted on the plate when plate is stationary . Homework EquationsThe Attempt at a Solution in the...

I've calculated the joint distribution, XY_PDF(x,y) of random variables X and Y (both coming from a distribution N(n) = C*e^(-K*n^2)). I use XY_PDF(x,y) to calculate the joint distribution AR_PDF(a,r) of the random variables A (angle) and R (radius), with the PDF method and the Jacobian. Since...

Homework Statement A boy slides on a sled on the curved track sketched (black line). (Treat the boy and sled as a particle.) His mass plus that of the sled is m = 41 kg. Friction and air resistance are negligible (I want a sled like that!). His initial speed is v0 = 1.3 m.s–1. The height h =...

Homework Statement the figure showed a jet of water , with velocity 50m/s strikes the flat plate , which is inclined 30 degree to the jet . Find the force normal to the surface of jet. Homework EquationsThe Attempt at a Solution my question is the flat plate is 30 degree to the horizontal...

Hi, I have this math problem where I need to find the scalar component of acceleration at a given time under certain conditions. Usually these problems aren't bad for me, but this one has left me scratching my head. Its giving me ||a|| = 4 and (aT)(T) = 5i +5j -k I have the formula aN =...

Hi, I'm not sure about the the normal vector N on a complex function z(x,t) = A e^{i(\omega t + \alpha x)} My approach is that (\overline{z} beeing the conjugate of z): \Re{(\mathbf{N})} = \frac{1}{\sqrt{\frac{1}{4}(\partial x + \overline{\partial x} )^2 + \frac{1}{4}(\partial z +...

Homework Statement A student sits a test and is told that the marks follow a normal distribution with mean 100. The student receives a mark of 124 and is told that he is at the 68th percentile. Calculate the variance of the distribution. Homework Equations...

Hey! :o Let $G$ be a non-abelian finite group with center $Z>1$. I want to show that if $G/Z$ is a $p$-group, for some prime $p$, then $G$ contains a normal $p$-Sylow subgroup and $p\mid |Z|$. We have that $$|G/Z|=p^n, n\geq 1\Rightarrow \frac{|G|}{|Z|}=p^n\Rightarrow |G|=p^n|Z|$$ That means...

Homework Statement Homework Equations relevant equations are provided with each question below The Attempt at a Solution please check my solutions to ensure they are correct. thanks. a) [/B] b) Calculate net force: Fnet = FA + Ff + Fg Fnet = (1.20 x 104 N [up]) + (1.40 x 103 N [down])...

Hey! :o I want to find a normal series of $D_4$ and all the composition series for $D_4$. I have done the following: $D_4=\langle a , s\mid s^4=1=a^2, asa=s^{-1}\rangle$ A subgroup of $D_4$ is $\langle s\rangle=\{s, s^2, s^3, s^4=1\}$, that is normal in $D_4$, since $[D_4:\langle...

If I have a system where the following is found to describe the motion of three particles: The normal modes of the system are given by the following eigenvectors: $$(1,0,-1), (1,1,1), (1,-2,1)$$ How can I find the corresponding eigenfrequencies? It should be simple... What am I missing?

Why is normal force always perpendicular to the surface? I understand that normal force is the upward reaction force by a surface due to an external action force pushing the surface. Then, if I apply an extermal force on a non inclined surface at an angle, let's say 30 degrees, shouldn't the...

Homework Statement A 22-gram mass is released from rest at position A on a stationary frictionless surface whose shape is that of a quarter circle of radius R = 0.66 m. (b) Determine the magnitude of the normal force that acts on the mass when it is at position B (it is at position B when the...

Homework Statement A multiple choice test consists of a series of questions, each with four possible answers. How many questions are needed in order to be 99% confident that a student who guesses blindly at each question scores no more than 35% on the test? Homework Equations So I know that...

Homework Statement A 60 kg skier is beginning her descent down a 26 degree slope. The frictional force between the skis and the snow is 4 N a) What is the gravitational force the skier exerts on the slope? b) What is the normal force the slope exerts back on the skier? Homework EquationsThe...

Am not sure if I've posted in the right section but I couldn't find anything relevant to Waves in Supersonic Flow, so apologise in advance! Post is a little long but I will appreciate any help! Academically am not very gifted and also have a mathematics disability so I tend to question even the...

\begin{eqnarray*} &&\mathbb{E}\left( 1_{\left\{ X_{1}+X_{2}>\rho \right\} }X_{1}X_{2}\right) \\ &&\mathbb{E}\left( 1_{\left\{ X_{1}+X_{2}>\rho \right\} }X_{1}^{2}\right) \end{eqnarray*} where ##X_1## and ##X_2## are independent normal variables. I am wondering whether there exist closed-form...

Homework Statement The ellipse is given as (x^2/a^2) + (y^2/b^2)=1 I´m meant to calculate a tangential vector, a normal vector and find an equation for the tangent using a random point (x0,y0). I´m meant to do this in 2 ways: firstly by using the parametrization x(t)=a*cos(t) and...

Hello! As far as I know any subgroup can, in principle, be used to divide group into bundle of cosets. Then any group element belongs to one of the cosets (or to the subgroup itself). And such division still is not qualified as a quotient. Yes, the bundle of cosets in this case will be...

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 :(

Hey! :o I want to find all the normal subgroups of $D_n$. We have that $$D_n=\langle a, s \mid a^2=1=s^n, asa=s^{-1}\rangle$$ We have that $K$ is a normal subgroup of $D_n$ iff $$gkg^{-1}\in K, \forall g\in D_n \text{ and } \forall k\in K$$ Could you give me some hints how we could find...

Hey! :o I want to show that $N\{1, (12)(34), (13)(24), (14)(23)\}$ is a normal subgroup of $S_4$ that is contained in $A_4$ and that satisfies $S_4/N\cong S_3$ and $A_4/N\cong Z_3$. Let $\sigma\in S_4$. We have the following: $$\sigma 1 \sigma^{-1}=\sigma (1) \\ \sigma (1 2)(3 4)...

Hey! :o I want to show that if $H$ is a cylic normal subgroup of a group $G$, then each subgroup of $H$ is a normal subgroup of $G$. I have done the following: Since $H$ is a normal subgroup of $G$, we have that $$ghg^{-1}=h\in H, \ \forall g \in G \text{ and } \forall h\in H \tag 1$$...

So say I have a truncated normal. That is, N(mu,sigma) that is from 0 to infinity only. I need to find a Gamma such that a constant C*Gamma(A,B) is always above N(mu, sigma). How would I go about finding such a A, B that would work given fixed mu and sigma?

1. The problem statement Hi, I just have a quick question on how to find the normal force in this picture on mass 2, http://postimg.org/image/w9sr29ab3/ , the half circle. Its a double pendulum with no friction. Can I assume that the normal force is in that position all the time as the half...

Find the standard score for a the data value 9 from a normal distribution which has a mean of 16.8 and a standard deviation of 2.3

So I have been asking my self these questions lately. I know it is some basics of physics and I should probably know the answer.. Why do we feel weightlessness when we hit the acceleration of gravity (9.8) exactly? Probably so that the surface that we are standing on doesn't need to produce any...

Homework Statement <I will attach a diagram below> In terms of m, g and r. FInd the normal force at the top of the loop. Homework Equations ∑F = Fc = FN+Fg ∴ Fc=FN+Fg ∴FN = Fc - Fg ∴ N=mV2/r - mg The Attempt at a Solution Fc=mV2/r - mg and V2=ra and a=g ∴C=mrg/r ∴C = mg ∴mg-mg=N ∴ N=0 N. BUT...

[Note: Thread moved by moderator] Hi! so I have a question I am unable to do and I've been trying it for 3 hours. The question had 2 parts, i figured out part a but cannot figure out part b. A) A 0.006kg ball is dropped from a height of 4.0m above the floor. Neglecting air resistance...

Hello, Does anybody know how to compute shear and normal stresses which take place due to applied load? My case is a simply supported beam (120x120x6.5 length: 4.2m) reinforced by a plate (20x120 length: 2m). Plate is welded on a top of a beam and external force (F=15 kN) is applied to the...

Homework Statement why the normal acceleration is 6 rads^-1 ? It's not stated in the question , right? Can someone explain more about normal acceleration? i couldn't understand it . I only know that when the rod is rotated , it has tangential acceleration Homework EquationsThe Attempt at a...

Homework Statement Let $$ \Phi(x)=\int_{-\infty}^{x} \frac{1} { \sqrt{2\pi} } e^{-y^2 /2} dy $$ and $$ \phi(x)=\Phi^\prime(x)=\frac{1} { \sqrt{2\pi} } e^{-x^2 /2} $$ be the standard normal (zero - mean and unit variance) cummulative probability distribution function and the standard normal...

If a car us on a frictionless banked track what causes the normal reaction force to be greater than the weight force? My understanding from what I've read is that the vertical component of the reaction force cancels the weight force which makes sense as the object doesn't leave the ground. And...

This isn't actually a problem. It is a doubt which I have about wedges according to Newton's Laws Consider a friction less wedge, of mass 'M', inclined at angle θ, placed on a smooth horizontal surface, on which a block of mass 'm' is placed. The block exerts some normal force perpendicular to...

so I got my sphere, centered at (1,-2,0) with radius 3 how do I put normal vectors/arrows onto my sphere's surface? I tried quiver3(x,y,z)

Hi Community, I have this question. I start by creating the derivative, \d{}{x}(x^2-xy+y^2) = \d{}{x}(3) and solve for \d{}{x}(3) = 0 (Derivative of a constant is alway 0) I understand how to solve the derivative of \d{}{x}(x^2-xy+y^2) and get 2x-y In the worked example it says...

Please can you help me with this question. A surface h in the three dimensions is given by the equation z=g(x,y) Find the unit normal at any point h in two separate ways: a)By identifying h with an equipotential for some scalar field φ to be determined and computing ∇φ. b)By expressing the...

Homework Statement Hey guys, I have been making progress in classical mechanics but I'm having a tough time figuring out how to solve for the normal frequencies for this set of equations of motion: http://imgur.com/nQKPNsu In order to account for the mass gravity term here the book suggests...

Homework Statement There are ##N = 10000## clients of an insurance company. One-half of them will file claims with probability ##p_1 = .05##, another half of them will file claims with probability ##p_2 = .03##. Each claim is worth ##$1000##. Find the Value-at-Risk at the level α = 0.99, that...

Gravity does act on a satellite so why is normal force 0 for an object placed inside it?