Change Definition and 1000 Threads

If there is a large mass near a black hole, is the event horizon teardrop shaped? Today I was thinking if it was possible to violate the idea that anything that passes the event horizon is gone forever. I forgot to label my picture, Figure 1 is the top and Figure 2 is the bottom. I imagine a...

I understand from my classes that, when looking to calculate the electric field of a charge we can use the electric field measured in its rest frame to find its electric field in the lab frame (where the charge is moving). The gamma factor changes the value for the component electric field if it...

Homework Statement A ripple tank is setup and a point selected on the second nodal line. determine the change in path length from two wave sources if they are in phase and separated by 2cm and the wave length is 5cm Homework Equations not really sure of what equations to use? The Attempt at a...

Homework Statement A force F = (2ti + 3t^2j) N acts on an object moving in the xy plane. Find the magnitude of change in momentum of the object in time interval t=0 to t=2 (The bold ones are vectors) Homework Equations Ft=change in momentum The Attempt at a Solution magnitude of F = (4t^2 +...

I understand the basics of how vision works, but correct me if I'm wrong at any point. Electromagnetic radiation is emitted from the sun as a byproduct of fusion, in the form of photons. These photons travel a vast distance at an incomprehensible speed, and bounce around the atmosphere a bit. A...

I teach high school physics and electronics. My experience is that no amount of instruction prevents students from accidentally blowing fuses when they're first learning how to measure voltage and current in a circuit. I would love to buy a classroom set of these...

Homework Statement If the bulk modulus for water at 70∘F is 319 kip/in^2, determine the change in pressure required to reduce its volume by 0.3%. Homework Equations E = dP/(dV/V) E - Bulk Modulus dP - change in pressure dV - change in volume V - volume The Attempt at a Solution Well I just...

Homework Statement Homework Equations $$PV^{\gamma}=\mathrm{constant}$$ The Attempt at a Solution Initially, the piston will get a velocity ##v##. But the chamber will move too because of the forces exerted by the gas. Since total external force is zero, velocity of centre of mass is...

Homework Statement A cord vibrates with a frequency of 3.0 Hz when a mass of 0.60kg is hung up from it. What is its frequency if only 0.38kg hangs from it? Homework Equations f= 1/2pi sqrt k/m The Attempt at a Solution 3.0= 1/2pi sqrt ( k/0.6) k=213.18 N/m f= 1/2pi sqrt (213.18/ 0.38) f=...

"For a particular flow rate, the pressure drop due to the downward flow of the fluid is balanced by the pressure gain due to gravity—that is, at this flow rate, the static pressure in the pipe is independent of the distance along the pipe." Book says this. Can you explain how the pressure...

How does change in pipe diameter affect pressure? For example, ethylene in a 6" pipe at 400 psi, enters a 1" pipe. How does the pressure change? I am fairly sure that pressure decreases and velocity increases. However, I need to know how pressure decreases? At what rate? Is it linear?

Homework Statement I need to rearrange the change in kinetic energy equation for mass Homework Equations Change in Kinetic energy = 0.5mv^2-0.5mu^2 The Attempt at a Solution I factorised the right hand side to give: Change in kinetic energy = m(0.5v^2-0.5u^2) Then: m = Change in...

Homework Statement A golfer sinks a hole-in-one on a mini-putt golf course. The ball leaves the putter face with a speed of 4.04 m/s, travels a distance of L1 = 4.38 m, and bumps into a bank with a speed of 3.34 m/s, rebounds at 90° and travels a length of L2 = 3.26 m into the hole. Assuming a...

Homework Statement Evaluate the integral ∫∫sin(x+y)/(x+y) dydx over the region D whereD⊆R2 is bounded by x+y=1, x+y=2, x-axis, and y-axis. Homework EquationsThe Attempt at a Solution I think that I need to use a change of variables but can not find any change of variables that work. One thing...

Hi folks, This is a question about how to calculate entropy change when there is a temperature change involved. I got the correct answer to this, but I don't actually understand why it's correct..! Any help is much appreciated. Homework Statement One mole of liquid bromine is heated from 30...

Homework Statement Q. [/B]The bob of a simple pendulum has a mass ##m## and it is executing simple harmonic motion of amplitude ##A## and period ##T##. It collides with a body of mass ##m_o## placed at the equilibrium position which sticks to the bob. The time period of the oscillation of the...

Homework Statement Hello all! I need a little bit of help with my physics homework! It asks me to calculate the change in volume produced by the piston, and it gives me the equation: ∆V= Ax∆dHomework EquationsThe Attempt at a Solution Now I know that A= 1x 10-^16m^2 And ∆d=1700nm My only...

Homework Statement See image attached. Oh it's part c by the way. Homework Equations maybe upthrust=weight of water displaced... None really relevant. The Attempt at a Solution I thought the balance would initially go up as the sphere entered the water, (but maybe slightly less than the...

I find most textbook explanations of resonance lacking. My understanding is that resonance occurs becuase less "driving energy" is lost when the driven frequency approaches the natural frequency of a system. But why does the energy loss curve like this? Since Q-factor is different for each...

Homework Statement Homework EquationsThe Attempt at a Solution [/B]

Homework Statement Homework EquationsThe Attempt at a Solution My problem is with part ii) To me, my logic seems sound for the rate of change of depth but apparently it's wrong. Does anyone see what I'm missing? Thanks

Hi, I'm working on a process control question about a tank system at steady state. The part I'm having problems with is where I have derived a second order differential equation to model the system and have replaced the concentrations with derivation constants in that : Actual Concentration at...

Homework Statement Homework EquationsThe Attempt at a Solution 6C-H bonds= 410 x 6 = 2460 kJ/mol 3C-C bonds H of formation= +53.3 kJ/mol H of atomisation = +717 kJ/mol H-H = 436 kJ/mol as H of formation is 53.3, can't I just do: 2460+3x=53.3? But then I am not using a lot of the values...

This is Exercise 2.20 in Nielsen and Chuang's Quantum Computation and Quantum Information, on page 71. Suppose $A'$ and $A''$ are matrix representations of an operator $A$ on a vector space $V$ with respect to two different orthonormal bases, $|v_i\rangle$ and $|w_i\rangle$. Then the elements...

Why isn't the second line in (5.185) ##\sum_k\sum_l<\phi_m\,|\,A\,|\,\psi_k><\psi_k\,|\,\psi_l><\psi_l\,|\,\phi_n>##? My steps are as follows: ##<\phi_m\,|\,A\,|\,\phi_n>## ##=\int\phi_m^*(r)\,A\,\phi_n(r)\,dr## ##=\int\phi_m^*(r)\,A\,\int\delta(r-r')\phi_n(r')\,dr'dr## By the closure...

Homework Statement A sample containing 3.65 mol of a monatomic ideal gas is heated from 289K to 458K, and the entropy remains constant. If the initial volume of the sample was 0.0980m^2, by what factor did the pressure increase or decrease during this process? Homework EquationsThe Attempt at...

Homework Statement Let: ##I=\int _{-1} ^{1}{\frac{dx}{\sqrt{1+x}+\sqrt{1-x}+2}}## Show that ##I=\int_{0}^{\frac{ \pi}{8}}{\frac{2cos4t}{cos^{2}t}}## using ##x=sin4t##. Hence show that ##I=2\sqrt{2}-1- \pi## Homework EquationsThe Attempt at a Solution The substitution is ##x=sin4t## which...

Homework Statement Two moles of an ideal gas undergo a reversible isothermal expansion from 3.37×10−2m3 to 4.29×10−2m3 at a temperature of 29.6 ∘C. What is the change in entropy ΔS of the gas? Homework Equations pV=nRT The Attempt at a Solution W=∫V2V1pdV, I don't know how to use this...

Homework Statement At a moment in time a particle has a velocity of v = 3 m/s î + 4 m/s ĵ, and an acceleration of a = 6 m/s2 î + 3 m/s2 ĵ. Find the rate of change of the speed of the particle, that is, find d|v|/dt. (better formatted reference...

usually, entropy change in solid and liquid is formulated as Cp(or Cv)ln(T2/T1) or Q/T(integral)+ Sgen. so, considering the former and the latter equations, Do their entropy changes include irreversibility due to Sgen? And next question, reservoir has no change in temperature and volume...

My question is: when oil and water from separate containers are poured into the same container and given time to equilibrate, is the entropy change positive, negative, or zero? I've been told that there is zero change in entropy because the water and oil do not mix at all. However, I suspect...

Homework Statement A 20 kg sample of mercury is completely solidified and liberates 231.6 kJ of energy. What is the original temperature of the mercury? (The melting point of mercury is 234K, the heat of fusion of mercury is 11.3 kJ/kg, and the specific heat of mercury is 140 J/kg•K.) . What is...

Good morning everyone! My chemistry final is approaching and I have a few difficulties in the thermodynamics chapter. One of the things that are bothering me is the calculation of the temperature of phase change. We know that if a mole of ice at 273K melts, the entropy change would be...

An ideal gas is compressed from a volume of Vi = 4.50 L to a volume of Vf = 3.00 L while in thermal contact with a heat reservoir at T = 295 K as in the figure below. During the compression process, the piston moves down a distance of d = 0.120 m under the action of an average external force of...

Hello, I have a typesetting software which can export typeset math as normal, nice looking black LaTeX text. However it always puts it on a white background. How can I change the background color of an image (png or jpeg) without changing the black text contained int he image? Should I write...

Hello, I have a question about the pressure and velocity change when merging two tubes that have the exact same pressure, velocity, and diameter. I've attached an image to give you guys a visualization. Say the three tubes are all laying flat on the ground, so there's no height change. What...

Homework Statement Assuming water to be an ideal gas, enthalpy of vaporization is x joules per mole. I have to find change in internal energy an 100 degree Celsius for one mole of water. also find heat absorbed. Homework EquationsThe Attempt at a Solution I initially thought that during...

From this diagram: If a conductor of length(##L##) is moving with a velocity(##v##) inside constant magnetic field(##B##), there is an induced EMF as indicated at the top of copper slab, and connected to a load and current will flow. I've been curious with the way the wires are connected to...

have read numerous times about Hawking radiation. don't understand how that can lead to black hole evaporation in so much that wouldn't as many matter as anti-matter particles fall in thus balancing out over time to the growth and evaporation of black holes thus leaving the mass of the balck...

Homework Statement hello, I have a problem that I couldn't find a clear answer to. Attached is a diagram of a related problem that explains the problem Air traveling through two tubes with the same direction have the same PSI (say 75). If you merge the two tubes into a tube with the same...

Homework Statement Find all ##{\cal C}^1(\mathbb{R}_+^\star \times \mathbb{R},\mathbb{R}) ## solutions to the pde ##x\frac{\partial f}{\partial y} - y \frac{\partial f}{\partial x} = cf##, where ##c## is a constant. Use a polar change of variable. Homework Equations Trying to bring the...

I am thinking about something that is getting me quite confused. To illustrate what is confusing me let's have a cart moving in the horizontal direction on a track without friction, and a motor which adjusts to keep the kart at a constant speed V in the positive direction. Now, it's snowing so...

if a ray of monochromatic light comes from a denser medium to a rarer medium does the color reaching a viewer in the rarer medium differ from the actual color of light in the denser medium (as wavelength of light is different for both the media)?

Homework Statement Hvap = 22.6E5 J/Kg. R=8.315E3 Jkmol^-1K^-1. 1kmol water = 18kg Keeping in mind that latent heats are enthalpies, what is the change in internal energy when 1kg water is converted to steam at pressure of 1atm and temperature of 100C. Homework Equations dU = dQ - PdV. The...

Homework Statement What is the entropy change of the universe as a result of the following processes: (a) a 1μF capacitor is connected to a 100V electrochemical cell at 0°C, (b) the same capacitor after being charged to 100V is discharged through a resistor kept at 0°C? Homework Equations...

Homework Statement All edges of a cube are expanding at a rate of 3 centimeters per second. How fast is the volume changing when each edge is (a) 1 centimeter and (b) 10 centimeters? Homework EquationsThe Attempt at a Solution I used the equation for the volume of a cube: V = s3 but I'm not...

Hello everyone, I still wonder if there's a change in entropy in adiabatic process. The definition of entropy is a quantity represents for the disorder state of a system. Arccording to kinetic theory of gas, temperature is for the state of chaotic motion of molecules. So I'm very confuse, can...

Homework Statement [/B] Consider ##\mathbb{R}^3## in standard Cartesian co-ordinates, and the surface ##S^2## embedded within it defined by ##(x^2+y^2+z^2)|_{S^2}=1##. A particular set of co-ords on ##S^2## are defined by ##\zeta = \frac{x}{z-1}##, ##\eta = \frac{y}{z-1}##. Express...

I believe I can explain why there is energy needed to break intermoleculares bonds and getting into a gas or liquid, but the other way around confuses me. Bonds have potential energy associated to it, so It's needed work to break the bonds, because we would be trying to move a molecule away from...

Homework Statement to illustrate an aspect of the second law of thermodynamics, we regard entropy changes in two cases. We have a vessel with 1 kg of warm water with T = 80 C and another vessel with 2 kg of cold water with T = 10 C and we mix them. Case 1: we pour hot water in the vessel with...