Normal Definition and 1000 Threads

Alright, I don't have a specific homework problem here, just a general question. I've attached two pages that I will be referencing. Figure 1. Inclined Plane As can be seen here, the FN = mgcos(∅) Figure 2. Banked Curve It seems as if the opposite is true here. FNcos(∅) = mg...

Scope of this thread is to give a complete as possible answer to the question proposed two days ago by the user simon11 on Basic Probability and Statistic forum... Assume two random variables X and Y are not independent, if P(X), P(Y) and P(Y|X) are all normal, then does P(X|Y) also can only be...

Hello, I'm David. I'm a new member here. Could anyone of you help me? Where can i find the formal deduction of Gauss' Normal Distribution Function? I've read a lot of statistics books and never found that. Where that comes from? It's just curiosity, not homework. P.S.: sorry about my...

I have heard 2 informal explanations for the normal force during a situation like a book resting on a table: 1. The springiness of the atomic lattice in the table attempts to restore its original structure, thus pushing the book. 2. Since there are electrons on the outside of both the...

[FONT=Lucida Grande]Assume two random variables X and Y are not independent, [FONT=Lucida Grande]if P(X), P(Y) and P(Y|X) are all normal, then does P(X|Y) also can only be normal or not necessarily? [FONT=Lucida Grande]thanks.

Homework Statement A ladder of length l and mass m leans against the side of a house, making an angle θ with the vertical. Assume that the ladder is free to slide at the point where it touches the side of the house (there is no significant friction). Find an expression for the normal force...

Anyone know answer to below. If two random variables X and Y are both marginally normal, and conditional distribution of Y given any value of X is also normal. Does this automatically mean the conditional distribution of X given any value of Y also has to be normal? or not necessarily.

Homework Statement What is a mechanism that might cause a rubber band or a string to develop tension in response to a force that you apply? What mechanism explains how walls and tables exert normal forces without bending noticeably? Homework Equations None, since this is a...

Homework Statement Let N(x) denote the CDF of the standard normal density. So, it's the integral of the standard normal density from -∞ to x. Is it true that \lim_{b\to 0} N(\frac{a}{b}) = N(\frac{a}{\lim_{b\to 0}b}) = N(+\infty) = 1? 2. The attempt at a solution This is more of a...

Ok forgetting everything about how Earth is not a perfect sphere, the greatest centripetal acceleration is at the equator. So if you say N - Mg = -Mac, N should equal M(g-ac) which gives a weaker force than the gravitational force. If the net force is a force towards the center of earth...

Let's say we have a point-normal representation of a space: n \cdot P_{0}P = 0 where n is a vector <a_{1},a_{2}...a_{n}> and P_{0} is a point through which the space passes and P is the set of all points contained in the space. In ℝ^{2}, the point-normal representation defines a line. In...

Homework Statement The Gravitron single-car roller coaster consists of a single loop-the-loop. The car is initially pushed, giving it just the right mechanical energy so the riders on the coaster will feel "weightless" when they pass through the top of the circular arc. How heavy will they...

General Question Here: Let's say you are swinging a ball around on a string. Will there be a normal force?

How do you calculate the Normal vector to an Ellipse. Radius Vector: r=rx*i + ry*j + rz*k Velocity Vector: v=vx*i + vy*j + vz*k at this point I would like to calculate the Normal to the ellipse. That is as far as I been able to calculate. Any help or suggestions are welcome.

Homework Statement find the normal approximation for the binomial probability P(x = 4,5) where n=14 and p = .5. Homework Equations μ = np σ = sqrt(npq) z = (x - μ)/σ The Attempt at a Solution p = .5 q = .5 μ = 14*.5 = 7 σ = sqrt(14 * .5 * .5) = 1.87 z = (4 - 7)/1.87...

This is my first problem set involving work, so I want to make sure I'm doing it right. Thanks for checking. Homework Statement To push a 25.0 kg crate up a frictionless incline, angled at 25.0° to the horizontal, a worker exerts a force of magnitude 209 N parallel to the incline. As the...

I was looking at this example: http://keep2.sjfc.edu/faculty/kgreen/vector/block3/flux/node10.html and was confused between the difference between \hat{}n and \vec{}r Why is the original vector field not given in terms of a unit vector? And what difference does this make? Thanks :)

Hi everyone, Defined the Fermi Normal Coordinates (which can be seen for example http://relativity.livingreviews.org/open?pubNo=lrr-2011-7&amp;page=articlese10.html" ) is there any heuristic argument to explain why the area element is something proportional to the element of solid angle? I...

Ok so I already know how to solve it by looking at an example my teacher did in class... This is what I did... 4. A 2.00 kg block is held in equilibrium on an incline of angle θ = 70° by a horizontal force vector F applied in the direction shown in the figure below. If the coefficient of static...

Graphics3D[Sphere[{0, 0, 0}]] How do I add a tangent plane and normal vector to this plot? I am not opposed to Matlab or Latex either.

You push a 8.00 kg suitcase across a smooth horizontal floor applying a force directed 35.4 degrees below the horizontal. Someone measures the acceleration of the suitcase to be 1.26 m/s2. Assuming g = 10.0 m/s2, what is the normal force the ground exerts on the suitcase? So is normal...

Homework Statement So the question is, given a set of random numbers, find the mean and the value that will be >= 99% of the occurances. So for a set of random numbers between say, 1-100, if the mean is 50, how do I find out what number will be >= 99% of all observations of the time...

Hi, I have a curve defined by following parametric equation \begin{equation} \gamma(\theta) = 1 + 0.5 \times \cos (N \theta) (\cos(\theta),\sin(\theta)), 0 \leq \theta \leq 2 \pi \ \end{equation} where N is an integer. x and y coordinate of any point on the curve are simply...

OK, this looks like a differential geometry problem, which it is, but at the end of the day I am trying to figure out why the unit normal and unit tangent vectors to a curve aren't orthogonal, so even if you don't know about DG, please respond. Obviously the two choices for E_1 and E_2...

Homework Statement Here is the question with the solution: The Attempt at a Solution I understand the first part where they find the forces by summation of moments. However I don't understand how they got that area. Why would they take the diameter (0.016) and subtract it from the length...

Homework Statement tall strongman of mass m = 93 kg stands upon a scale while at the same time pushing on the ceiling in a small room.If the scale reads 1062 N (about 239 lb), what is the magnitude of the normal force that the ceiling exerts on the strongman? Homework Equations N=m...

Homework Statement The question ask to find E[X]; E[X^2]; Var(X) for the standard normal distribution f(x)=1/\sqrt{2\pi}e^{-x^2/2}Homework Equations I found \begin{align} E[X]&=\int_{-\infty}^\infty \! x*1/\sqrt{2\pi}e^{-x^2/2} \, \mathrm{d} x\\ &=1/\sqrt{2\pi} ( \int_{-\infty}^0 \...

Homework Statement Your friend's car broke down. You push it to a repair shop 2.0 km away. You gently put your car's bumper against the broken car's bumper and accelerate to a speed of 2.5 m/s over the course of 1 min. If the broken car's mass is 1200 kg, what is the normal force between the...

1. The homogeneous square body is positioned as shown. If the coefficient of static friction at B is 0.40, determine the critical value of the angle theta below which slipping will occur. Neglect friction at A. The image: 2. NA is the Normal force at A, which is perpindicular to the...

Hi all, I need help regarding the following expression: E(x1|X>K) where: x1 is a one dimension normal rv X is multivariate normal rv with n components: x1, x2,..., x_n K is a n dimension constant vector with n components: k1,k2,...,k_n X>K <==> x1>k1,x2>k2,...,x_n>k_n I know there is...

Homework Statement A tennis player slices the ball to spin and deviate from its normal parabolic path. What is an explanation for this phenomenon? I am having trouble visualizing the phenomena that is occurring with the slice and as well as the explanation give by the book. How is the...

Here is an example in which the normal force would not be counted as an action-reaction pair. A 100g block is sitting at rest on a horizontal table. According to Newton's third law, which of the following indicates the correct action-reaction pair of the two forces? So I was stuck between C. The...

Homework Statement The 2000 mm long composite bar shown in Fig. 1 consists of an aluminum bar having a modulus of elasticity EAl = 70 GPa and length LAl = 500 mm, which is securely fastened to a steel bar having modulus of elasticity ESt = 210 GPa and length LSt = 1500 mm. After the force P...

Hi there, I have performed a multiple regression analysis and I am checking the assumptions. The normal probability plot is not exactly a straight line, but is it okay? If you were looking at the plot would you be satisfied hat the normality assumption is valid...

Hi all, I've been working on a little side project, but I've hit a road block on the maths for this one. Basically if you imagine a sealed pack of 10 cards, there is a 20% chance that the pack contains one foil (more valuable) card. The mass distribution of the foil cards are (heavier and)...

Hello, My question stems from a research project of mine involving taking the normal modes of clusters of molecules from a potential. I was curious of the interpretation that can be made of normal mode vectors at a non-equilibrium structure, i.e something following a MD trajectory beginning at...

I'm programming a process that runs in iterations with a probability of stopping at every iteration. As it gets closer to the desired run-time, this probability should increase so that if the process is run many times over, the runtimes will form a normal distribution, with most of them having...

Hi, I have a rather basic question: most 'cosmic rays' have an energy of about 109 eV, but there are also 'Ultra-high-energy cosmic rays' with an energy of around 1019 eV to 1020 eV, so I was wondering if they couldn't be the result of collisions of two 'normal' cosmic rays that hit each...

Homework Statement I've attached the question. Homework Equations μ=np and σ=√(np(1-p)) Im using the normal distribution function on my calculator to avoid using z tables The Attempt at a Solution The mean I calculated it to be 160/4 = 40. standard deviation...

Hi, I am doing research and I am stuck at this point I need help to convolute iid non central chi-square with normal distribution.

Homework Statement Given position vectors: OA ( i + 2j - k) ; OB ( -i + 2j +3k); OC ( 2i + j + 4k) Given that OA is perpendicular to OB. The Question : Show that OA is normal to the plane OBC. Homework Equations r . n = d To find the normal of the plane OBC, I used n = BO x...

Homework Statement If we are simply standing on the ground will our normal force be always equal to our weight besides when we are jumping or when we land on the ground from a fall? When we are in an elevator, will the normal downwards force on the floor be of our weight (cancelling out our...

For a normal distribution with E[x]=0 and Var(X)=1, how do we determine the Z-value of a particular percentage ? i.e. if the percentage is 5%, how do we know that Z(5%)= 1.645 ? is there a calculation involved or do we get it from observing the x-axis of the normal distribution ?

Homework Statement Find the flux of the following fields: F_1 = xi + yj F_2 = -yi + xj across the following curve: The circle r(t) = (cost) i + (sint) j t is from [0,2pi] Homework Equations Flux = ∫F dot n ds = ∫M dy - N dx The Attempt at a Solution For F_1 I got: M = x =...

Hello. I am new to electronics and physics. Since injuring my back at work, I now have a lot of time on my hands to learn about the things that facinate me. So please forgive me for any wrong terminology or spelling and grammar mistakes. I have recently made a small jacobs ladder using a lm555...

Hi, I am trying to find a resource that can explain how σ and ∏ lines obtain their polarizations. I have not found resource that actually show the calculation or solid explanation that show this.The references are usually state that σ and ∏ have circular polarization and linear polarization...

Other than the obvious case of the (real or perceived) pressure of a full bladder eventually becoming unbearable, under what conditions do healthy people, i.e. those who do not ordinarily suffer from incontinence, lose bladder control? I know of two - extreme fear and choking/strangling. In the...

Suppose we have a normal distribution and a sample of n values from the normal distribution. To estimate the variance we can use the standard sample variance formula ( average squared distance from the mean divided by either n ( biased estimator ) or n-1 ( unbiased estimator ) ). There is...

help me find this normal vector! Homework Statement Find a normal vector n and the equation of the tangent plane to the surface S at the point x0 S: z=ln(x2+3y2) x0=(2,-1,ln7) Homework Equations The Attempt at a Solution ok so I have this general formula from the textbook. z=...

Hi all, I'm a little confused about Bloch modes vs. waveguide modes of a single waveguide and was wanting some pointers. I read that Bloch modes are results of the wavefunction of a particle (usually, an electron) placed in a periodic potential. In the case where we have an array of cylinder...