Change Definition and 1000 Threads

Homework Statement We can make a rough estimate of how much the envelope of a red giant should expand as a result of the contraction of its core based on conservation of energy. We will consider a star of mass M and initial radius R, with a core of mass Mc and radius Rc. We will focus on the...

A metal block at 500 K is kept on a large ice slab at 273 K.The metal block completely sinks inside the ice slab. I was told that the water in contact with ice would not change its temperature while the block sinks down and hence the "only" heat transfer from the metal block to ice slab will...

So my question is, if the bulk modulus change by 5%, what is the fractional volume change value? is it times 0.05 or divided by 0.05? or the fractional volume change still the same?

in calculating the delta p in vacuum chambers do we substitute p1 with 0 or the whole equation doesn't exist if air doesn't exist?

I know that if I multiply e^3/2 (e= 1.602x10^-19) to the unit below I can change it to eV Can somebody help me I don't know why

The problem is: The temperature (in degrees Celsius) of a metal plate, located in the xy -plane, at any point (x, y ) is given by the function of two variables T(x, y ) = x sin y + y2 sin x. (a) Find the rate of change in temperature in the direction of the positive x-axis at the point (π, π)...

For a real mass-conserved(m dot is constant throughout the system) steady-state mono-substance(same substance throughout) flow , what are the different factors which can cause stagnation pressure and temperature to drop/rise?

Why does ∆S = 0 for a reversible process, but for a reversible isothermal process, ∆S is given by nRln(Vf/Vi) (or other variations of that equation)?

So I have to prove "If (AxB)∩(BxA) ≠ ∅, then (A∩B) ≠ ∅." I wanted to prove by changing it's form. P = (AxB)∩(BxA) ≠ ∅ and Q = (A∩B) ≠ ∅ . The conditional statement is P implies Q and the new statement is not P or Q . P → Q = ¬ P∨Q They are equivalent. But how do I negate P? Would it be...

A hot object in thermal contact with a cold one will finally reach a temperature in between. Why can the entropy change of each object be calculated as if the process was reversible? Is there a reversible process with the same final and initial state and what would that be?

Homework Statement Two balloons are connected by a faucet. Gas in the first balloon is at pressure p_1=100kPa, and in the second is p_2=0,5MPa. Volumes are V_1=0,12m^3 and V_2=0,5m^3. Temperature of a gas is constant. Find pressure in balloons p after faucet is opened (balloons are not...

My question is simply..if force does equate to the rate of change of momentum, then why is it not taughted as this rate rather simply a push or pull? Is it becuase really they are the same thing and it is much easy to explain/work with? Just curious Guess up until now I didn't even think of...

What compounds,reactions and factors cause modern day paint to change hue intensity over time? Any help appreciated.

I'm trying to write a simple script in blender python in order to show load deflection in cloth simulation. My question is: Is it possible to translate the change of length (distance between two nodes), into a force? (Newton between those nodes)? In addition you will find a minimal example. The...

(1) Maybe should've messanged this, but given LIGO, the FAQ might need a light edit. It says, "Gravitational waves have never been detected directly, but the loss of energy from the Hulse-Taylor binary pulsar has been checked to high precision against GR’s predictions of the power emitted in...

Homework Statement A well insulated container consists of two equal volumes separated by a partition - one half an ideal gas while the other is a vacuum. The partition is removed, and the gas expands. What is the entropy change per mole? Homework Equations dS = dQrev/T S/R = Cp/R dT/T -...

Let's say ##f(x)=ax^2##. Then ##d^2f/dx^2=2a##. Now we can make the change of variables ##y\equiv\sqrt ax## to give ##f(y)=y^2##. Then ##d^2f/dy^2=2##. It follows that ##\frac{d^2f}{dx^2}=a\frac{d^2f}{dy^2},## but I can't replicate this with the chain rule. I would put...

There are two examples: A planet rotating around a star and a spacecraft maneuvering through space. Let's assume that solar radiation has no affect on the spacecraft and the spacecraft is not bumping into any stuff, and niether is the planet; and no other gravitational sources are involved...

Homework Statement Kevin and Jake collide in the air. If Kevin undergoes a 4.2 kg*m/s change in momentum, what is Jacob’s change in velocity if he has a mass of 83.2 kg? Homework Equations p=mv MV+mv=MV'+mv' The Attempt at a Solution I tried the simplest way possible... p=mv v=p/m v=4.2/83.2...

My thermo teacher was talking about 2 phase rankine cycles and he said the once water boils at atmospheric pressure its temperature can not get higher than 212 no matter how much heat you add. He said the only way you can raise the temperature of steam past 212 F is the raise the pressure. Why...

Hey people. First of all, I'm now in the third semester of my course in Mechanical Engineering. I have interest in aerospace/aeronautics, so there are plenty of things in mechanical that I like - fluid mechanics, aerodynamics - and that was the reason I choose this undergrad. Nonetheless, I do...

Homework Statement A 1 m3 rigid tank has propane at 100 kPa and 300 K. The tank is connected to another 0.5 m3rigid tank which has propane at 250 kPa and 400 K by a ball valve. The valve is opened and both tanks come to a uniform state at 325 K. Calculate the change in internal energy and...

Sorry about the title, had a hard time trying to fit the question on the given space. The question is quite simple : If F = F(x_1,...,x_n,t) , Under what conditions is \frac{d }{dt} \frac{\partial F }{\partial xi} = \frac{\partial }{\partial xi} \frac{dF }{dt} true?

Homework Statement I want to find the mathematical proof to show that the density of an object changes with thermal expansion. My professor showed this in class and it was horribly wrong because he let a few things out. The book I'm reading showed it in 4 steps and left out a lot of the crucial...

Homework Statement A 12kg shopping cart rolls due south at 1.5m/s. After striking the bumper of a car, it travels at 0.80m/s at 30. degrees E of South. What is the magnitude and direction of the change in momentum sustained by the shopping cart? Homework Equations p = mv The Attempt at a...

If the mass of an object is the same, does the inertia ever change. For example, is the inertia of a person different if they are on the surface of the Earth than if they are orbiting Earth or in outer space?

Homework Statement 1.If the ship has a mass of 2.5 x 10^7 kg calculate the magnitude of the force acting on the ship during the deceleration. I was trying to work that out using f=ma but that would Make the force negative , is that possible 2. What is the nature of the force acting on the...

Hi, When a molecule makes a transition from high energy state to low energy state, it emits electromagnetic radiation with a certain wavelength, which can be collected as emission spectrum. However, I have a question right here: For any real case, there are quite a number of molecules in one...

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 [FONT=Times New Roman]I factorised the right hand side to give: [FONT=Times New Roman]Change in kinetic energy...

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...