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33 views

Gyrocompas equation

Ok, need a little help for part (b) of the following problem. I set my axis similar to figure 113 and have expressed both $\omega$ and $\Omega$ in terms of the new coordinates. I have been told to ...
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2answers
449 views

How do I express the interaction energy between two charged spheres?

Consider two identical insulating spheres each with radius $R$ and uniform charge $Q$ through their volume. They are separated from their centers by a distance of $d>2R$. Here is my general ...
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0answers
227 views

Thermodynamics shell-and-tube heat exchanger

A shell-and-tube heat exchanger is used to cool a flow of steam using a stream of cooling water cooling water. The steam enters the heat exchanger at $0.1 ~bar$ and a quality of $91$% , and exits as ...
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0answers
102 views

Correct way to calculate torque produced by axle

For my electrical engineering course, we had to build a simple DC motor that can lift a coin. I have tested the motor, and here are the results: rotational speed (no load): 3630 RPM (380 rad/sec) ...
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0answers
100 views

Quantum Hamiltonian commuting with the Pauli-Runge vector

I have to prove that $[A_j, H] = 0$, with; $$\vec{A} = \frac{1}{2Ze^{2}m}(\vec{L} \times \vec{P} - \vec{p} \times \vec{L}) + \frac{\vec{r}}{r}$$ $$H = \frac{p^2}{2m} - \frac{Ze^2}{r}$$ And, $Z, e, ...
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0answers
45 views

Stagnation point from complex potential

I just wanted to see if I am doing this right. $$\Omega(z) = U(z+\frac{a^2}{z})$$ So to find the stagnation point: $$\Omega'(z) = U(1-\frac{a^2}{z^2})=0$$ Therefore stagnation points occur at: ...
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0answers
227 views

A force F pushes an inclined plane M with a block on the incline; find acceleration up the incline

So there is an inclined plane of mass $M$ that is pushed with a force $F$. A block of mass $m$ is on the inclined plane that accelerates up along the inclined plane due to the pushing of $M$ by force ...
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1answer
75 views

Simple circuit with resistances

I have a question about a circuit that I made in class! So, we had a circuit with 2 resistors, one of $R_1 = 330 \Omega$ and one of $R_2 = 470 \Omega$. The tension applied to the circuit should be ...
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0answers
40 views

What are some common errors when it comes to measuring hall voltage of a semiconductor?

What are some common errors when it comes to measuring hall voltage of a semiconductor? I've thought of two errors: Adjusting the potentiometer so that the width of the conductor would start with 0 ...
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0answers
99 views

g as a function of Theta

I slide an object down a ramp of a certain length, which is inclined at a certain angle $\theta$. It reaches the bottom in time $t$. Assuming that no forces act on the object other than gravity and ...
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0answers
88 views

Why does an armature of a generator rotate?

Why does an armature of a generator rotate? a) like poles repel b) unlike poles attract c) current flows up d) an outside force turns it I am thinking that (d) is the correct answer but ...
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1answer
97 views

How does volume of water in closed system relate to humidity at 25(C) degrees

If I have a closed system with a volume of 100L, at ~24(C) or ~75(F) degrees, what volume must be filled with water to reach a humidity of 90%? I imagined if you fill it 100% with water, humidity is ...
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0answers
185 views

Current Carrying Wire Loop near Current Carrying Long Wire

A rectangular wire loop of (width $a$ and height $b$) carrying clockwise current $I_1$ is a distance $d$ below a horizontal infinitely long wire carrying a current $I_2$ to the right. What is the ...
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3answers
204 views

Projectile motion formulas

Assuming: The equations for the vertical and horizontal components of my initial velocity. Are: $v_{x,i} = v_i \cos\theta$ and $v_{y,i} = v_i \sin\theta$ And the displacement components are ...
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1answer
143 views

Elastic collision of photon [closed]

Consider an elastic collision of a photon with 100 eV energy hitting a mirror. How much momentum is exchanged in the collision? Also, can one model the reflection of an elastically colliding photon ...
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0answers
22 views

Galactic flux given magntiudes

Introduction I have the following data for a galaxy: apparent magnitude in $U,B$ and $V$ Johnson photometric system: $$m_{U}=17.51 \\m_{B}=17.08 \\m_{V}=16.74 $$ The galaxy is such that the ...
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0answers
61 views

How to derive the equation in my question? [duplicate]

How to derive the equation in my question?
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0answers
158 views

Hydrogen atom in partial differential equations, show it is is independent of time. [closed]

For the hydrogen atom, if $\int|u|^2\ \mbox{d}x=1$ show that the same is true at all later times. Hint: Differentiate the integral with respect to t, taking care about the solution being complex ...
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1answer
56 views

Parametric equations of a hypersurface

In light-front QFT, in the Minkowski space, we define a hypersurface, $\Sigma_+ : x^3+ x^0 = 0 $. How can I write its parametric equations?
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3answers
1k views

Lowest point of a loose cable with a pulley/mass hanging from it [closed]

This is part of a homework question which I've been stuck on for several hours. I've tried googling "lowest point of rope", "lowest point of hanging cable", "lowest point of pulley", and a bunch of ...
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1answer
320 views

Frame of Reference Question

I'm having trouble understanding this frame of reference question. You are traveling in a car going at a constant speed of 100 km/hr down a long, straight highway. You pass another car going in ...
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0answers
83 views

What does “define analytically” mean?

I'm trying to do my homework in physics but here I have found something that I am not understanding. It says: Define analytically the terms that should stationary flow accomplish. I know that ...
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0answers
103 views

Pressure Rise in Closed Tank with 2 Inputs

Supposing you had a cylindrical closed tank inside the body of a submarine; the top of the tank is at 200m depth. The tank has height 2.5m and internal volume 1.8m^3. A section of pipework is ...
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1answer
1k views

Projectile motion, what is the relation between initial angle and speed at a given distance [closed]

I am trying to understand the relation between the initial angle of a projectile and its initial speed, given that the distance this projectile will travel is fixed and at the same height as the ...
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0answers
219 views

Angular Frequency about stable equilibrium

So I have the potential energy defined as: $$U(x)=U_0[2(\frac xa)^2-(\frac xa)^4]$$ And I want to find the angular frequency of oscillations about the point of stable equilibrium. I found the point ...
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1answer
230 views

Simple Acceleration Problem throwing me off

I am having trouble with this problem from my homework. I have gone over it many times, and I must have some concept wrong. A rocket is launched from the ground with constant acceleration. After 4 ...
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0answers
31 views

Uniform distribution of charge on a plane and on a bar: conditions to have no motion of the bar

On the plane z=0 there is a superficial charge distribution such that $\sigma$ is constant. Near to the plane, there is a bar, charged uniform with total charge q. At the extremities the bar has two ...
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0answers
123 views

Calculating Integrated Precipitable Water using GPS

I'm trying to calculate the Integrated Water Vapor (IWV) using GPS data. I'm following the equations in the following publication: GPS Meteorology: Remote Sensing of Atmospheric Water Vapor ...
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2answers
5k views

Simple rope tension problem

I have this really simple rope tension problem that can be solved for seconds using simple logic. I know what the answer is, I know why it is, but I cannot write it down and explain it mathematically. ...
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1answer
181 views

Coffee filter experiment: time as a function of mass

In an experiment I performed, I dropped $n$ amount of coffee filters from a constant height and recorded the time $t$ taken for the $n$ coffee filters to reach the ground. In the experiment, the value ...
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0answers
201 views

Resistance of circle of wire

Today I was wondering about this situation. Let's imagine I have a circle of wire with a homogeneous section. I connect the wire with 2 terminals from ohmmeter. What minimum and maximum resistance can ...
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3answers
674 views

How to determine direction of forces in a static problem?

I am consistently getting this wrong. To me, in the picture below, it would make sense that the structure would be pulling downward, and the cable BD would be pulling upward - thus the system is in ...
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0answers
189 views

How to find the angle of elevation and launch speed? [closed]

A particle is projected from a point on level ground with a speed of $u$ meters per second and an angle of elevation $\theta$. The maximum height reached by the particle is $42$ meters above the ...
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votes
1answer
90 views

Cylindrical charge distribution [closed]

I'll just list the problem first and then explain what I need help with. Consider a cylindrical charge distribution extending from $r = 0$ to $r = 8.2 $cm of charge density $\rho = r/a_0$, where ...
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2answers
740 views

Pressure and height of water in a pipe [closed]

In a building, at what height does water rise from the ground-floor in a pipe, if the pressure there measures P=3atm? The correct answer is 31m. What formula should I apply?
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0answers
60 views

Which pressure to use in the $T~ds$ equation?

Let's say I have an adiabatic, rigid, open container that has an amount of air at some pressure, $P_\text{cv}$, and some temperature, $T_\text{cv}$. I have heated pressurized air coming into the ...
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1answer
235 views

Accelerating fluid filled container [closed]

A container filled with fluid is accelerating initially with a1 and instantly changes to a2 (a2 < a1). What would happen to the fluid in the container. My thoughts on this - If the velocity of ...
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votes
2answers
471 views

Lever Counterweight of uneven weight distances

So, I have a camera crane that has a pivot leaving 2 distances, 0.5mts and 1.5mts respectively. Plus a small L-shaped piece of metal and the end of d2 (1.5) which holds a camera, which I suppose I ...
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0answers
84 views

positron / electron annihilation - where is the invariant?

Electron and a positron are headed towards each other with same kinetic energies - observed from center of mass (COM) system. After the colission two photons are emitted and are headed in opposite ...
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0answers
53 views

Kaon spontaneously splits into two pions (just need an confirmation)

I just need a confirmation on a problem that I am dealing. In my problem I have a statioary kaon which spontaenously splits into two pions which are headed in different directions. Is it possible to ...
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0answers
355 views

Scalar field lagrangian in curved spacetime

I am studying inflation theory for a scalar field $\phi$ in curved spacetime. I want to obtain Euler-Lagrange equations for the action: $$ I\left[\phi\right] = \int ...
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0answers
93 views

Angular momentum contained in E&M fields

I am trying to do this question as a prep for my quals and find my solution too simplistic. I fear I am missing something important. "Iron atoms (atomic mass 56) contain two free electron spins that ...
0
votes
1answer
692 views

Electric field outside a hollow cylindrical conducting shell [closed]

Imagine that a point charge $+Q$ is located at radius $R$ and height $z=0$ inside of an infinitely long conducting cylinder shell of inner radius $a>R$ and outer radius $b$. From what we know of ...
0
votes
1answer
73 views

Find the distance from the initial location [closed]

Sing Huat drives a car with initial speed 30 km/h and acceleration 2 km/h2 toward Tee, whose displacement is 200 m away from him. At the same time, Tee drives another car toward Sing Huat with ...
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0answers
320 views

Is it possible to solve a 2D relative motion question using components of relative velocity?

This is a question based on concepts of two dimensional motion . Here's how the question is: A plank A is floating in air, gravity has no effect on it (See its coordinates in the figure attached). ...
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0answers
35 views

Quantum tunelling problem - got a weird imaginary ratio in the end

1. The problem statement, all variables and given/known data Beam of electrons with energy $10eV$ hits the potential step ($8eV$ high and $0.5nm$ wide). How much of the current is transmitted? ...
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2answers
280 views

Law of conservation of energy and kinetic energy: deformation of a spring [closed]

Problem: A block B of 1,5 kg is attached to the right of a spring (not deformed, with its right side attach to a wall) with a constant of $k = 80 N/m$ and, at rest, the block enter in collision with ...
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0answers
23 views

What are physical effects that could be employed to emulate this system?

This is a simple system consisting of a tree of numbers such as ((1 2 (3 4)) (2 6) 1 6) and a rule of application, that states that a tree A applied to B is a copy ...
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1answer
425 views

Gas mixture flow rate equation [closed]

2 gas flows connect and mix in a pipe. The following is known: $\dot{m_1}$; $\dot{m_2}$ - mass flow rate of the inlet gases $(\frac{kg}{s})$ $A_1$; $A_2$; $A_{mix}$ - the cross section of the pipes ...
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0answers
82 views

nuclear physics- Energetics and Mechanics of Nuclear Reaction Homework

A sample of $^{24}_{12}\mathrm{Mg}$ is bombarded by a monoenergetic proton. If the resulting nucleus in a $^{24}_{12}\mathrm{Mg}(p,\gamma)$ reaction; $^{24}_{12}\mathrm{Mg}(p,\gamma)$ has its ...