Normal Definition and 1000 Threads

Say i Have 1. A perfectly spherical and perfectly rigid Ball 2. A perfectly flat and perfectly rigid wall Say i throw the ball at my FLAT wall also giving the ball a linear velocity The only contact with the wall and the ball is a point... a POINT ! So, I can as well forget about the rest of...

How does one find the normal force when the object is not at constant movement or at rest.

Homework Statement Consider the field extension Q(c):Q, where c is a primitive nth root of unity. Is this extension normal? Homework EquationsThe Attempt at a Solution I believe this polynomial splits in x^n - 1,where it's n roots are exactly the powers of c. Thus this extension is normal...

Hey! :o Let $E/F$ be a finite Galois extension and let the chain of extensions $F = K_0 \leq K_1 \leq \dots \leq K_n = E$. Let $G = Gal(E/F)$ and, for $i = 0, 1, \dots , n$, let $H_i$ be the subgroup of $G$, that corresponds to $K_i$ through the Galois mapping. I want to show that, for any...

Often when I ask questions in class, people laugh at them, so I stopped asking. What can I do? Am I more brain damanged than I think? I don't think university or any place is the place for me. I never see others or met others who talk or think like me, it makes me very angry and sad. Yesterday...

Homework Statement let b be a square root of 1+i, show that Q(b):Q is not a normal extension. Also, what is the Galois group of the extension? Homework EquationsThe Attempt at a Solution so b = +/- (1+i)^(1/2), and it's minimal polynomial is x^4+4 which has roots -(2)^1/2 and 2^(1/2) that are...

Hey! :o I want to show that each extension of degree $2$ is normal. I have done the following: Let $K/F$ the field extension with $[F:K]=2$. Let $a\in K\setminus F$. Then we have that $F\leq F(a)\leq K$. We have that $[K:F]=2\Rightarrow [K:F(a)][F(a):F]=2$. There are the following...

https://scontent-dft4-1.xx.fbcdn.net/v/t35.0-12/14796269_10210868496286479_1115393743_o.jpg?oh=0ccd692c60a1d0bab84d5fbaf7e6197b&oe=580A1894 In the figure, a 6-kg box is sliding up an incline that makes an angle of theta=30 degree (with respect to the horizontal). As it slides up the incline, a...

Hello, I came to know that a normal component of the viscous stress can exist at a solid surface for unsteady, compressible flows(though even in that case, the normal component of the viscous stress is typically much smaller than the tangential component). I tried googling it myself but could...

Two questions I had: 1. How is the force of friction of the tires pointed inwards to cause centripetal acceleration? If the tire is rotated when trying to turn, the car is still traveling with a velocity perpendicular to the circle and force of friction would still be counteracting the...

Homework Statement 2. The attempt at a solution Let rightward acceleration of the block (A+B) be $$a$$. Let downward acceleration of block (A) be $$a'$$ down. For block A: $$mg-T=ma'$$ $$N+ma=0$$ For block B: $$T+N=Ma$$ On solving $$N=-\dfrac{m^2g}{M+2m}$$ by taking $$a=a'$$.But...

Homework Statement Homework Equations at = Rα an = V2/ R = Rω2 Vt Rω Vn =0 The Attempt at a Solution I found at=0 an=5.66 m/s vt=3.364 vn=0 So v = vt = 3.364 m/s[/B] Correct?

Homework Statement For σBC end , i don't understand how the author get (20mm)(40mm-25mm) = 300x10^-6 (m^2) ... Homework EquationsThe Attempt at a Solution IMO, , the area should be the circled part (thin rectangular part of the rod) , but i only know one dimension only , which is 40mm , i don't...

Homework Statement For the curve with equation y={ x }^{ 2 } at the point (1, 1) find the curvature, the radius of curvature, the equation of the normal line, the center of the circle of curvature, and the circle of curvature. Homework EquationsThe Attempt at a Solution \kappa \left( 1 \right)...

I'm just looking for any tips one might have for finding normal modes quickly? The GRE always seems to have a question or two on them and I have no idea how they expect someone to do a problem like that in the time given. I know that there is normally, in the problems given, a symmetric and an...

I love physics and maths,I am17,from Malaysia...My questions:Should I have a high IQ to study physics in university?Is it useful in the future?Are there many girls like to study physics?Or I am a weirdo? Haha, just kidding.I need answers and thank you!I hope Albert Einstein always...

Eleanor scores 680 on the mathematics part of the SAT. The distribution of SAT math scores in recent years has been Normal with mean 547 and standard deviation 85. Gerald takes the ACT Assessment mathematics test and scores 27. ACT math scores are Normally distributed with mean 21.3 and...

I have answered Q1-Q3. I am unsure of my answer for Q4 and am stuck on Q5. Notation: \(I^*=Gal(K:I)\). That is the subgroup of G=Gal(K:F) that fixes I. Q4. I2 is conjugate to I1. iff \(\exists i \in G:I_2=i(I_1)\) iff \( I^*_2=[i(I_1)]^*=iI_1^*i^{-1}\) by Q3. iff \( I^*_2=iI_1^*i^{-1}\) iff...

Homework Statement The two blocks (m=16kg and M=88kg) are not attached to each other. The coefficient of static friction between the blocks is us=0.38, but the surface beneath the larger block is frictionless. What is the minimum magnitude of the horizontal force F required to keep the smaller...

hello guys, i have a question and looking for an answer quickly... question; prove that, Z is a vector.thank you.

Homework Statement If the normal at P(ap^2 ,2ap) to the parabola y^2 = 4ax meets the curve again at Q(aq^2, 2aq), show that p^2 +pq+2=0 Homework Equations Point-slope form The Attempt at a Solution I tried putting y=2aq and x=aq^2 but I can seem to simplify the whole thing other than...

I have just gone through chapter 14 on the QFT for the gifted amateur by Lancaster and Blundell. Quantising the electromagnetic field results in the Hamiltonian: $$\hat{H}=\int d^3p \sum^{2}_{\lambda=1} E_p \hat{a}^\dagger_{p\lambda} \hat{a}_{p\lambda}$$ with ##E_p=|p|##. In this post ##p##...

Why during a banked curve is the horizontal component of the normal force considered as the net force and the centripetal force? The horizontal component of Normal force, N·sinθ, is not even ponting towards the centre of the curvature.

Hey all, I've had this point of confusion for a bit and I have thought that with time I may be able to clear it out myself. Nope, hasn't happened. I think I need help. Let us say we have the following \phi_{k+1}=\phi_{k}+v_k where, v_k\overset{iid}{\sim}\mathcal{N}(0,\sigma^2) and...

Homework Statement The relationship between the expected value and the variance for a particular normal CDF is known to follow the rule ##E(X)=arcsin(ln(Var(X)))##. Given that ##Pr(0.32<Z<2.32)=Pr(12.9<X<74.275)##, determine the possible values of the mean and the standard deviation correct to...

Homework Statement http://ocw.nthu.edu.tw/ocw/upload/8/256/Chapter_7-98.pdf refer to page 3 in the 2nd, 3rd pictures, i have problem of finding σx'Homework EquationsThe Attempt at a Solution why can't use the formula to find σs ? it's given that σx' = ( σx+ σy)(0.5) + (0.5)( σx- σy)cos2θ +...

Homework Statement http://mathwiki.ucdavis.edu/Core/Calculus/Vector_Calculus/Vector-Valued_Functions_and_Motion_in_Space/The_Unit_Tangent_and_the_Unit_Normal_Vectors In the link, I can't understand that why the Principal Unit Normal Vector is defined by N(t) = T'(t) / | T'(t) | ,can someone...

Homework Statement when the normal vector n is oriented upward , why the dz/dx and dz/dy is negative ? shouldn't the k = positive , while the dz/dx and dz/dy is also positive? Homework EquationsThe Attempt at a Solution is the author wrong ? [/B]

Homework Statement ##r(t)=(t^2)i+(1+\frac{1}{3}t^3)j+(t-\frac{1}{3}t^3)k## Find the tangential, normal, and binormal vectors for this TNB frame. Homework Equations ##T(t)=\frac{v(t)}{|v(t)|}## ##N(t)=\frac{T`(t)}{|T`(t)|}## ##B(t)=T(t)×N(t)## The Attempt at a Solution The problem isn't that I...

Hello PF members, I just wanted to initiate a discussion about this topic. It always has bugged me and I don't ever like something like this to happen to me. So the whole point is that I (Personally) keep forgetting what I studied in math for the past year. It is not because I didn't...

Homework Statement Suppose that the number of asbestos particles in a sam- ple of 1 squared centimeter of dust is a Poisson random variable with a mean of 1000. What is the probability that 10 squared cen- timeters of dust contains more than 10,000 particles? Homework Equations E(aX+b) =...

Hello, My title is a little too long. I have graduated two years ago in applied physics at a master level and did nothing since then. I am isolated and I feel a lack of motivation to apply for PhD offers (and never had any motivation to apply for any other kind of job offers) and I lack...

Homework Statement why the angle of shear stress ( θs) is given by θp - 45 ?? Homework EquationsThe Attempt at a Solution the difference in angle of shear stress and normal stress is90 degree , am i right? why it's negative 45 degree? is it wrong?

I have two surfaces that have a coifficent of friction of .6. Disregarding mass (if possible) at what angle would the force of static friction and the normal force be equal

Homework Statement why the shear stress is maximum at the center ? while the normal stress is maximum at the boundary ? Homework EquationsThe Attempt at a Solution why shouldn't the shear stresss maximum at the boundary ? this is because shear stress is to pull the 2 surface apart [/B]

Homework Statement An ##D## meter long wooden stick with a mass of ##M## is placed on two chairs of neglegible lenght. The left is ##L## meters from the left end and the right is ##X## meters from the right end. Find the expression for the both Normal forces that act from the chairs. Homework...

Homework Statement a ball is thrown from some height horizontally with some velocity. After 1 second what is its normal acceleration? Ignore air friction Homework EquationsThe Attempt at a Solution I was absolutely certain that it is 10m/s2 couse that doesn't change and it has no acceleration...

For the following question, how do we know that the acceleration of ##M## is constant over time? And is the normal contact force between the two masses smaller as compared to that where ##M## is fixed? The acceleration depends on the net force on ##M##, which depends on the normal contact...

So, my question is what does the "normal" part mean when one talks about normal frequencies and normal modes in coupled oscillations. Does it have to do with the normal coordinates that one uses when solving some problems, or with normal in the sense of orthogonal. Thanks for your help.

I am working on a physics engine, and I have a question about the collision normal. There are a lot of different ways people say to calculate this, perpendicular to the collision angle, perpendicular to the edge of body 'B', etc. I was wondering if it would be okay to assume the collision...

I understand that every force has an equal and opposite reaction, and the reason things can move is because the forces acts on different things. Also, F=MA is why the heavier object is accelerated less. The equal and opposite reaction to gravity pulling down towards the Earth's core on a book...

Hi all. I'm trying to figure out how is the normal (direction) applied by two disks on a rod which connects the two disks, in order to build the second law of dynamics. See figure. Hope you could help Thanks

I think I miss something about energy of a mechanical wave. In absence of dissipation the mechanical energy transported by an harmonic wave is constant. $$E=\frac{1}{2} A^2 \omega^2 m$$ But, while studying normal modes on a rope, I find that the mechanical energy of a normal mode (still...

Let's say we have r=R( theta, phi, t) on the surface of the particle and need to find the normal vector in Spherical Coordinate system. We know that, the unit vector =grad(r-R( theta, phi, t)) / |grad((r-R( theta, phi, t))| where grad is Spherical gradient operator in term of e_r, e_\theta...

Hi there, I have a question that I think has an answer but I cannot find it in the literature in any convincing way: I am using two models, WKB based and TMM based to calculate the transmission probability of electrons through a (initially rectangular) thin potential of the order of 1-2nm...

[MENTOR note] Post moved from General Math forum hence no template. Assume that a random variable follows a normal distribution with a mean of 80 and a standard deviation of 24. What percentage of this distribution is not between 32 and 116? My approach is to calculate the Probability for (mean...

Homework Statement The time Rafa spends on his homework each day is normally distributed with mean 1.9hrs and standard deviation σ. On 80% of these days he spends more than 1.35 hours on his homework. i. find the value of σ ii. find the probability that Rafa spends less than 2 hours on his...

Homework Statement Homework Equations ΣF=0 The Attempt at a Solution Basically I don't agree with this solution, I think it is R1 + R2 - mgcos5 + mv^2sin5/r = 0. Can you help me please? thanks!

What is the equation of forces please for the axis parallel to the banked road? Is it R1+R2-mgcosθ=mV^2/r or R1+R2-mgcosθ=-mV^2/r? Can you advise me please?

I am given the sphere V= x^2 + y^2 + z^2 =< 1 I have converted it to spherical coordinates: x = rsin(t)cos(f) y = rsin(t)cos(f) z = rcos(t) where t ranges from 0 to pi, and f ranges from 0 to 2pi. I am unsure how to go about this problem from here. Any guidance would be really appreciated :)