Change Definition and 1000 Threads

I've been trying to wrap my head around the relationship between temperature increase of an object at a distance and temperature of a heat source. From what I've found, the temperature increase of an object from thermal radiation is affected by the inverse square law...

Let's introduce a time-varying scalar field ρ(x,y,z,t) [charge density] and vector field J(x,y,z,t) [current density] Assuming the system follows Maxwell's equations, what must both fields satisfy such that ##∇⋅(\frac{∂B}{∂t})=0## ?

Hi all, I am very confused by this concept. As I searched online, all respondents say that friction decreases as angle increases because normal force decreases. BUT, they don't explain this phenomenon: A block on a ramp is static at certain angle, and after the ramp is raised by a certain...

Homework Statement Just a general physics question that I was thinking about. I posted it here because I assumed it is a general question that is easy to most experts. I apologize if something similar was posted before, but I couldn't find anything asking in a way I needed to think about it...

Homework Statement Homework Equations The Attempt at a Solution There is solved problem on change in water height with respect to time. I understand it but there is the b part of the question. It asks that what's if the top of the tank is open to the atmosphere? I think nothing would...

why change of volume in pure torsion is zero? if you consider stress in plane with degree of 45 there is normal stress normal stress can lead to change of volume

Homework Statement 2NOCl(g) <--> 2NO(g) +Cl2(g)[/B] What will be the effect on equilibrium concentration of NOCL when equal moles of NOCL and NO are introduced in the mixture at constant temperature? Homework Equations Kconcentration = [NO]2[Cl2] / [NOCl]2 The Attempt at a Solution In my...

Hi, I have an optical model, fully programmably controllable with python. I want to know how much my variables (say N) of my model impact a certain parameter (i.e power, abberations). Now I have no clue how to go about this. There must be some analytical (numerical) method that I could use but...

According to my physics book light changes speed in different mediums such as water. Doesn't the speed of light have to remain constant? Thanks in advance

After looking at the "doppler effect" explanation of the twin paradox, I'm under the impression that the difference in the age of the two twins has to do with the part of the diagram where one of the twins is accelerating. But, my question is, what about the "coasting" part of the diagram? So...

Lets say I have a coil that is 1cmx1cm in area that gets heat up. I am told that I get 2W/cm^2/sr output. So if I had 100 of them in an array, the total radiant intensity would be (2W/cm^2/sr x 100 x 1 sqcm =) 200W/sr. Now, let's say I add a parabolic reflector around each coil. How would I...

Good day to all, Hi, i would like to ask if there is a way to calculate the temperature change at a given time. I will use this as a basis for my study which is about designing an ice container and i would like to know how long does my ice last given its own temperature and the outside...

Homework Statement Suppose we drop a lead ball of mass M into water of mass m from a height h and allow everything to settle down. What is the temperature change of the water? Assume that the container is well insulated. Homework Equations Potential Energy = mgh dU = mcdT where dU is the...

I have a small motorcycle and have changed the incandescent bulbs to LED. It seems the bulbs were powered by AC off the magneto generator and AC thru the rectifier powered the 6 volt battery. Is it ok to run LED this way or should I add diodes like in option a or b of diagram?

Ok, so I could do an experiment on this first, but I decided to see if anyone knew beforehand. So basically my question is will different properties of the same temperature, exposed to the same temperature, cool/heat at the same rate? For example would a more viscous liquid cool as fast as...

Torque ##\tau## should be in the same direction as the change in angular momentum ##\Delta L##, but the following example seems to suggest otherwise. Consider a cone rolling on its side without slipping on a flat surface. Let the apex be the origin and the initial coordinate of the center of...

Homework Statement Consider a closed, adiabatic system consisting of a mixture of liquid and solid substance Z at equilibrium at its melting point. Z (solid) <---------> Z (liquid) Which of the following statements is true regarding the system? A) The entropy of the system is at a maximum...

Homework Statement Use the change of variables to evaluate the integral (x +y ) sin(x -y )dA, where R is the region enclosed by y = x, y = x - 2, y = -x and y = -x + 1. (Hint: use u = x + y and v = x - y Homework EquationsThe Attempt at a Solution Not sure how to start it

so I've been taught basic rearranging of formula which I've found easy now I am given questions which are obviously a lot harder and I've entered the mind black hole if you could point me in the right direction with this where I go wrong make L the subject $f=\frac{1}{2\pi}$...

Homework Statement 1 kg of moist air and 1 g condenses. What will the change in the temperature of the moist air be? Heat of Vaporization = 2.5*10^6 J/kg 2. The attempt at a solution The moist air will warm due to condensation. Heat of Vaporization=2.5*10^3 J/g Specific heat at...

my understanding of beta radiation is that an up quark in a proton changes to a down quark, forming a neutron and emitting an electron as the result of the change in charge. My questions are, 1. Why does the quark change? 2. How does it change and how does it change charge?

Two Thermally insulated cylinders, A and B, of equal volume, both equipped with pistons, are connected by a valve. Initially A has its piston fully withdrawn and contains a perfect monatomic gas at temperature T, while B has its piston fully inserted, and the valve is closed. Calculate the final...

So I was busy trying to imagine the ways in which lenz's Law would work physically. So I imagined a loop through which a magnet is brought and after that the magnet is pulled out of the loop a current is induced in order to keep up the magnetic field. So in this case the flux would go down which...

I have encountered this form of a function: ##f \left(x, y\right)##. Later throughout the discussion, the function was represented as ##f \left(y \right)##. Does this change in representation imply anything? I have been looking through the discussion if ##x## was considered constant, but it...

i am not asking for a diagnosis or anything , but it it impossible for one to change his bad simple habbits . for example if someone is used in eating like a savage and he does not chew his food , can this person become normal ? and if someone is not organised at all , can this person become an...

Use change of variables to evaluate the following integral $$\int_{2}^{7}\frac{x}{\sqrt[3] {x^2 -2 }} \,dx\approx 8.577$$ $u={x}^{2}-2$ $du=2x\ dx$ $\frac{1}{2}du=x\ dx$ $u(2)=2$ $u(7)=47 $ $$\frac{1 }{2 }\int_{2 }^{47 }\frac{1 }{ \sqrt[3] {u }} \,du $$ Can't get same answer

Homework Statement Multiple choice:[/B] In which of the following processes are covalent bonds broken? a) solid sodium chlroide melts b) bronze melts c) sucrose dissolves in water d) solid carbon graphite sublimes e) solid carbon dioxide sublimes Homework Equations none The Attempt at a...

Does anyone know how to change the format of the answers given in the scratchpad? For example, when converting degrees to radians, ##177^{\circ}(\frac{\pi}{180})##, I want the calculator to give me ##\frac{59\pi}{60}## instead of 3.08923. Any help would be appreciated! This has been really...

Homework Statement Consider a quantum particle of mass m in one dimension in an infinite potential well , i.e V(x) = 0 for -a/2 < x < a/2 , and V(x) =∞ for |x| ≥ a/2 . A small perturbation V'(x) =2ε|x|/a , is added. The change in the ground state energy to O(ε) is: Homework Equations The...

I am trying to calculate the spring rate for an air filled shock-absorber, however I am struggling to get my head around the change non-linearity at the start of compression. Obviously if the shock is fully extended then it will be applying no compressive force to the chassis so that accounts...

If you drop a permanent magnet like steel through a copper tube it induces an emf, this is because you have a change in magnetic field/flux? But how? Why? The copper isn't producing a current before the magnet is dropped into it... Does something happen with the electrons in the copper?

An automobile tire has a pressure of 210kPa at 20.0 degrees celsius. What will be the tire pressure after driving for some time if the temperature rises to 35.0 degrees celsius. The equations we have are P1*V1/T1 = P2V2/T2 V1/T1=V2/T2

I'm trying to understand the nature of coordinate transformations in physics. In classical mechanics, we can transform to a different coordinate frame by means of a Galilean transformation. In special relativity, this is replaced by a Lorentz transformation. I am now wondering whether there...

Homework Statement Two rigid, insulated tanks are connected with a pipe and valve. One tank has 0.5 kg air at 200 kPa, 300 K and the other has 0.75 kg air at 100 kPa, 400 K. The valve is opened, and the air comes to a single uniform state without any heat transfer. Find the final temperature...

Homework Statement If two objects of unequal mass and unequal Kinetic energy hit each other, they lose some energy to other forms but keep enough to do Work on each other. A good example is a car and wind, a man and ball could also apply, a ball with KE could stop a running man if KE does work...

I obtained an extra factor of ##\frac{1}{l^2}## in the first term on the LHS of (3.34). From (3.33), LHS ##=u^2\frac{d}{d\theta}(\frac{u^2}{m}\frac{du}{d\theta}\frac{dr}{du})-\frac{l^2u^3}{m}## ##=u^2\frac{d}{d\theta}(-\frac{1}{m}\frac{du}{d\theta})-\frac{l^2u^3}{m}##...

Homework Statement we know the mass of the moon, Mm, and the Earth's, Me, and also the initial distance between their centers as the moon orbits the earth, Rem. Now if the earth’s angular velocity about its own axis is slowing down from a initial given angular velocity, ωi to a final angular...

I can't seem to find anything online that talks about this distinction. I understand how when the water gets shallower that part of the wave gets slowed down so the overall alignment parallels with the shore. However, I wouldn't think that would change the actual direction of the wave. I need a...

A trolley is moving at a constant speed down a track, with no net force acting upon it. A heavy load is dropped vertically on top of the moving trolley. What happens to the trolley's speed? a) It stays the same, b) It decreases, c) It becomes zero, d) It is impossible to say, e) It increases...

Hello, I have a simple question. Has the discovery that some neutrinos change their flavor posed any issues with conservation of energy?! How has this been solved?! Thank you.

can a resultant external force on a body change its mass but keep velocity of its centre of mass constant ? Is it practically possible - ##\vec{F}_{ext}=\vec{v}_{com}\frac{\mathrm{d} M}{\mathrm{d} t}## where F is nonzero

What change in velocity would be produced by an unbalanced force of 2.4 × 10^4 N acting for 6 s on a 2.0 × 10^3 kg dragster? Not sure how to setup this problem Equations i have are as follows: Fnet = mass × acceleration Velocity2 = velocity1 + acceleration × time Distance = velocity1 × time +...

Hello, My professor just gave us a True or False problem that states: ∇H(x,y), the gradient vector of H(x,y), gives us the largest possible rate of change of H at (x,y). Now, he said the answer is true, but it was my understanding that the gradient itself gives the direction of where the...

Homework Statement Hey guys, I'm just going through a Laurent series example and I'm having trouble understanding how they switched the index on a summation from n=0 to n=1 and then switched the argument from z^(-n-1) to z^n as well as changing the upper limit to -infinity. If anyone could shed...

Homework Statement I have a particle which is initially in a bound state for a given voltage in the form of a delta function at the origin, V = -αδ(x) initial state is ψα = (√αm)/h2*exp(-m*α*|x|/(h2) At t=0, voltage is changed to V = -βδ(x) both α and β are greater than zero. Right now I'm...

In my textbook it says an isothermal process occurs when the temperature is constant. It also said taht typically, Q,W, and delta U are not 0 in these processes. My question is how can heat not be 0 if temperature is constant? Q=mcDeltaT so if Delta T is 0, then Q also has to be 0 right?

Hello. What would you think of the international scientific community calling to change all negatively charged particles to positive and vice versa? Do you think there's a circumstance where we should switch or should have switched? The only reason I brought this up is that it came up when...

Homework Statement Q The length of a simple pendulum executing SHM is increased by 21% .The percentage increase in the time period of the pendulum of increased length is a) 11% b) 21% c)42% d)10% Homework Equations ##T = 2\pi\sqrt{\frac{L}{g}}## The Attempt at a Solution ##T^2 =...

Consider the following set of vectors in $\mathbb{R}^3:$ $u_0 = (1,2,0),~ u_1 = (1,2,1), ~u_2 = (2,3,0), ~u_3 = (4,6,1)$ Explain why each of the two subsets $B_0 = \left\{u_0, u_2,u_3\right\}$ and $B_1 = \left\{u_1, u_2, u_3\right\}$ forms a basis of $\mathbb{R}^3$. If we write $[\mathbf{x}]_0$...

Homework Statement A 1 liter container is filled with argon to pressure of 10^5Pa at 303K. Dropped into pool at temp 323K. How much heat is needed to heat the gas to 323K? what is the entropy change in the gas and the universe? ignore the entropy change in container. Homework Equations...