Confusion Definition and 1000 Threads

The equation of trajectory of ball B is y = -0.05x^2 where y is vertical displacement and x is horizontal. Prove that the ball is projected horizontallyFor this, the mark scheme says x tan a = 0 so a =0 Since the angle between ball and surface is 0 the object is projected horizontally. I can't...

Do electrons become more likely to be found in certain places as the temperature approaches 0K?

In my physics textbook chapter of work 3 statements are made which I am having trouble sorting through. 1. When W>0 the system's energy increases, when W<0 the system's energy decreases. 2. ΔE = ΔK+ΔU+ΔTherm = W 3. ΔU = -W Here is where my confusion begins. If I move a 1kg brick from 0m to 1m...

https://lh3.googleusercontent.com/0GOyZeQMdpLgYxYwwP4FMabe-Mk7QpADPC4ZK4PVpBGKvamcqjopOf3M0evdhE8PHZ3iTQ=s138 m1 is 4 kg and m2 is 8 kg. The kinetic friction coefficient on the table is 0.3. m1 is held in place. When m1 is released, m2 accelerates 1.2 m to the floor. Use conservation of...

According to my professor's model answer for an assignment, when we derive the transfer function of an op amp circuit, we have a "K" value, which is the open loop gain of the op amp (I am not 100% certain), multiplied to the op amp circuit (1+R1/R2 for non-inverting amplifier for example). I...

I have a dilemma, which has been nagging at me for a week. So first off, can anyone verify my definitions are correct? Heat is the flow of energy, and that flow is caused by the collisions of the atoms in a system. The collisions cause a transfer of KE, hence heat will flow from a substance...

Homework Statement I encountred a question that says : Assume that gravitational interactions between galaxies in groups lead to random galaxy velocities of 300 km/s At what distance would the redshift predicted by Hubble's law dominate over that produced by individual velocities? and what is...

i am trying to push myself and learn these furTher exercises in my maths i would any appreciate any comments and help. Question 1 what is probability u happens if n happens... P(U INTERSECTION N) / P(U)? Question 2 probability of U or S happening in the sample space of UDP or 52 byte size...

I don't understand the concept behind equation (1). I think that the equation V=-Nd(flux)/dt is only for magnetic induction. However the power of the primary coil is usually supply by an a.c. power source. (So as to provide a changing B field.) Therefore, it is not an induction process. How can...

I've been given the following relations where as I understand it subindex 2 equals subindex e and subindex 1 equals subindex i: ***EDIT*** More accurately subindex 1; initial state of a control mass subindex 2: end state of a control mass (end state is simply state 2 in the problem at hand)...

Hi, It's a real life math question and this seems the best place to ask. Me and my friend started a business together on 50% partnership bases. (cost divided by both and profit shared by both). My friend was lacking some money, so I added additional amount to cover his share. It's a garments...

Hi, Excuse me this is probably a really stupid question but I ask because I thought that the definition of the dimension of a space is the number of elements in the basis. Now I have a theorem that tells me that ## dim M_{k} = [k/12] + 1 if k\neq 2 (mod 12) =[k/12] if k=2 (mod 12) ## for ## k...

Ok, I'm reviewing my real analysis and found a point of confusion. So for a sequence S(n) to converge to S, for every e>0 there exists N such that n>N implies |S(n)-S|<e. Ok that makes sense. However when I backsolve and find N as a function of epsilon, and then formally proving forwards, I'm...

Hi, I'm a bit confused regarding what steps to take to answer the following question: In 8 years, a new library is being opened. Expenses are estimated to be $52,000, payable at the end of each month. If all funds earn 14.4% compounded monthly, how much money needs to be invested today, to be...

Homework Statement ##d=0.52 cm,## ##\lambda=431nm##, ##L=119 m## Homework Equations ##dsin\theta=(m+1/2)\lambda## for constructive/bright fringes since there is a pi shift already The Attempt at a Solution a) $$sin\theta\leq1$$ $$(.0052/431e-9)-0.5=m=12064$$ 2 \e{3} $$ total bright fringes =...

Hello I'm working through transposing formulae of pearsons Anthony Croft and Robert Davidson's foundation maths 5th edition and I'm stuck on exercise 10.1 question 1)e) We're it states that I must transpose the formula to make x the subject. The formula is y = ¹/₂x and the answer x = ¹/₂y I...

There is waterpipe with smooth interior wall as shown in the figure.The curve of waterpipe could be describe as function ##q_y=f(q_x)##. A ball going through this pipe was put at ##O## point with zero initial speed.At the point ##(q_x,q_y)##,the speed of the ball could be decomposed as...

Maybe, it's a useless question. The figure which I'm talking about consists of two parallel lines each of length 'b' and are separated by a distance 2r. Their ends on one side is closed by a semicircle which in pointing inwards and decreases the area and the ends on the other side are joined by...

1. Must the electron brought to rest(in one step or many steps) in Bremsstrahlung effect? 2. Besides from a coming electron knocking off an electron on the shell then another electron fills the void, can the coming electron just excite an electron on the shell to a higher state and release a...

It was only the psychrometry came; I read about vapour pressure is equal to the saturation pressure at 100% relative humidity. While before even in the textbooks both terms are used frequently as same. I fully understood what saturation pressure is; learned during phase change phenomenon of...

I have run into some serious confusion with a seemingly very simple problem: A car is going around a circular track, the road is banked, and there is no friction. For this case all texts state that the centripetal force is caused by the normal force, i. e. by the radial component of the normal...

In Quantum Field Theory by Lancaster, equation 3.14 $$ [\hat{a_i},\hat{a_j}^\dagger]=\delta{ij}$$ is introduced as "we define". Yes, example 2.1, where the creation and annihilation operators applied to harmonic operator states, there is a nice simple proof that this is true (although...

Ok so here is the problem. Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 3, which has a goat. He then says to...

Hi, I know that UDP does not preserve ordering. This means two messages sent maybe received in order different to the sending order. But how a message preserves order within itself. If it breaks the message into packets how these packets unite to form a message similar to the message sent. Or...

I've lately began working with Newtons laws problems at school again, and I've already ran into a few problems. When making calculations and solving problems, it is often nessecary to understand when forces are equal to zero, and when they are not. Since every force has an equal and opposite...

Homework Statement Hi there, what is the difference between the partial derivative and the total derivative? how do we get the gradient "the actual gradient scalar value" at a point on a multivariable function? what does the total derivative tell us and what does the partial derivative tell...

Homework Statement Determine Currents ##I_{1}, I_{2}, I_{3}## Homework Equations Kirchoff's Rules: $$\sum_{i=1}^n I_{i} = 0$$ $$\sum_{i=1}^n V_{i} = 0$$The Attempt at a Solution Basically, I'm not sure if I'm applying the Loop Law correctly. For example, in Loop A, going clockwise from...

The empty set has a cardinality of 0, yet it is found in all sets and as we know any sets within a set are counted as a single element. But it never counted as an element in the cardinality of a set? For example: The set {1,2,3} contains 8 distinct subsets including the empty set, as taken by...

So what's the smplest illustration for voltage ,current and resistance and what's ohms law ?

#mark contains personal comments and thoughts # BTW this assignment was a beginner exercise at codeacademy intended to test the usage of if-structures # I was wondering about whether or not if-structure was going to work, or if I needed a loop-structure becauses I wanted to interrogate the...

In the photo that is a matrix B. B^3 + B = 2B^2 +2I from calculations. But why not B must be equal to 2I, the reason is as follow, B(B^2 + I ) = 2(B^2 +I) B(B^2 + I)(B^2 + I)^(-1) = 2I (B^2 + I)(B^2 + I)^(-1) so B = 2I why is my concept wrong? please explain to me.

Why some quantities are multiplied by using dot product and some by cross product ? Like work done is calculated by scalar product of force and displacement while torque is calculated by vector product of force and position vector?? Why do we give directions to quantities like angular velocity ...

Homework Statement This HW is a continuation of the previous lab work we did involving, rings,spring scales and weights. The three hypothesis the groups came to were: 1.The ring will move in the direction of the interaction and will slow down. 2.The ring will move in the direction of the...

Hi all, I am learning about the vacuum Rabi frequency for the first time in Metcalf's book Laser Cooling and Trapping (Section 2.2). I am trying to make sense of the following two equations Metcalf gives: $$\hbar \Omega_{S} = -\vec{\mu} \cdot \vec{E_{\omega}}$$ and $$\vec{E_{\omega}} =...

This is from a general relativity book but I think this is the appropriate location. The proof that \nabla_{[a} {R_{bc]d}}^e=0 is as follows: Choose coordinates such that \Gamma^a_{bc}=0 at an event. We have \nabla_a {R_{bcd}}^e = \partial_a \partial_b \Gamma^e_{cd} - \partial_a...

Homework Statement ------------------ Homework Equations V=IR KCL/Node Voltage The Attempt at a Solution These are the solutions to some old homework assignments that my teacher posted, but I am very confused on the way he labeled his current flows in these problems. In the first picture...

Homework Statement Homework Equations V=IRThe Attempt at a Solution This problem is really confusing me. For VL(0-) and IL(0-), the voltage and current when t<0, wouldn't both those values just be 0? the 0- means before the switch is closed right? So before it is closed the right branch...

I understand what time invariance means but there are a few catches that I'm completely confused about: Suppose we have $$y(t)=x(\alpha t-\beta)$$ to test time invariance we shift the input then "plug" it into the output:$$x_1(t_1)=x(t-t_o)$$ so this is when I become confused; when we plug...

In Woodhouse's 'General Relativity' he finds an expression for the energy-momentum tensor of an isotropic fluid. If W^a is the rest-velocity of the fluid and \rho is the rest density then the tensor can be written as T^{ab} = \rho W^aW^b - p(g^{ab} -W^aW^b) for a scalar field p. The...

Homework Statement Manually[/B] trace the following code segments assuming that x equals 12. Show exactly what would be displayed on the terminal. if (x > 0) { printf("x>0\n"); if (x < 10) { printf("x<10\n"); if (x == 12) { printf("x==12\n"); } }...

Homework Statement Homework Equations Loob Analysis V=IR The Attempt at a Solution So I think I have the right equation here, but I am a bit confused on some parts. I am not too sure why i2=i1-ix. The way my professor explains it doesn't make much sense. Also (TYPO) in the second...

Homework Statement Homework Equations Node Voltage Method V=IR The Attempt at a Solution So I am very confused about the node voltage method. For this example, the first equation makes sense to me. Current in equals current out. 6A in and then the rest makes sense. Is this how you do...

The definitions of electromotive force of a cell that i have read include: 1.When no current is drawn from a cell,i.e., when the cell is in open circuit, then potential difference between the terminals of the cell is its electromotive force. 2.The electromotive force of a cell is defined as...

Recently I started studying semiconductors and analogue electronics. First I studied the diode and its I-V characteristics and analysis in DC circuits, as well as in AC circuits. Now I started with BJT transistors. I was explained that transistors act as electronic switches. My problem is not...

The main question stems from the answer for this one: If I have a light year long rod and push it on one end, how long would it take for the other end to move? Still Unsure of this answer. Main Question: If I had 2, light-year long conductive rods with a voltmeter attached at the ends then...

When a loop rotates in a magnetic field, does it have to actually "cut" the field lines in order to have emf induced in it? I mean if the loop is rotating and there is a rate of change of flux in the loop, does this mean that the loop is also "cutting" the field lines? I know if the loop is...

Hello there, I've just been learning about surface magnetization currents circulating around hypothetical square loops. Since the magnetization is uniform the circulation currents cancel where the square loops are adjacent to one another and it can therefore be said that the current circulates...

Hi! I'm currently studying Griffith's fantastic book on QM, and I'm confused for a bit about the wave function for a free particle. Here's what I think so far; for a free particle, there are no stationary states, so therefore we can't solve the SE with...

In E2=m2c4+p2c2 how do you prove light has momentum? I've tried but my answer comes to be undefined. Light has m=0, so you're left with p2c2. p=(mv)/sqrt(1-v^2/c^2) When substituting values of light you get that p=0/0. How do you prove light has momentum using math and equations?

I've found online that the coherent state of the harmonic oscillator is |\alpha \rangle = c \sum_{n=0}^\infty \frac{\alpha^n}{\sqrt{n!}} | n\rangle where |n\rangle = \frac{(a^\dagger)^n}{\sqrt{n!}} |0\rangle and |0> is called the initial state. I've some code where I need to have this...