What is Change: Definition and 1000 Discussions

Why if a young person like 21 years old with no degrer made a new discovery in theoretical physics like an equation or a theory will not be accepted by people and no one will believe him ? What he should do before to let people accept his discovery ? Can it be accepted if that person was not...

Homework Statement The full range input of a12-bit, successive-approximation type ADC is 1 volt. Determine: a) the maximum input change required to give a one bit change in output of the ADC Homework Equations None The Attempt at a Solution The ADC is 12 bit, so it will produce a...

http://imgur.com/BNQPAQa I'm missing something. Why does x+1/x suddenly become x-1/x2? I get that they moved the x to the top, subtracted the -1-1, but does that exclusively set the fraction negative all on its own ? I've computed it by hand. 1-2 comes out to be 1... So why is it negative... ?

Ok, this will be awkward but i somehow got lost in this thought, For low velocities, the formula for energy boils down to the classical E=1/2m*v^2 So let's say two astronauts A and B are in empty space absent of gravity. B has a jetpack and accelerates to 5m/s which require E=1/2m*v^2=...

I'd like to read some articles, papers, or whatever scientific there is about the prospects and impacts of climate change for professional ground based astronomy and observatory sites. In particular, which locations which are now among the most suitable sites for observatories - especially...

If I add 1402kJ of energy to 1 mol of Nitrogen I will ionize it, as I understand it. So when I ionize it, will it actually change the velocity of the ionized atom? What about the overall temperature of the gas?

Dear all, Interested in change phase, I would like to set a simulation to understand the multiphysics phenomena of heat storage in a shell and tube tank between hot water as the heat transfer fluid and a PCM ( phase change material) using the commercial CFD software Fluent. The purpose is to...

So if energy levels, or eV of electrons, do not change with molecular bonding, how are electrons influencing each other.? In glass, when individual atoms of silicon, sodium, and calcium come together, to form glass, the molecular bonding does not change the energy levels of the electrons for...

Homework Statement Hi everyone, this is probably simple but i don't understand why the acceleration in the question is 0.20 m/s2 but in the answer an acceleration of 0.020 m/s2 is used? Can someone please explain why it changes? Thank you! Homework EquationsThe Attempt at a Solution

How is a top gate used to change electron density in 2D semi conductors? I get the principle, you are just shifting the chemical potential by some voltage so that there are more or less electrons in the specific bands. But how is it physically done? Thanks.

if i sucked air out of an oil well after drilling a few feet and closed the hole by any means and continued drilling without allowing air in, will that eliminate change in influx and won't result in a kick? or because i can't suck air completely out so the delta p will be really high?

Hello Community My first post here so excuse me in case i posted in the wrong place. I basically have to write a paper in school about a physics topic. This includes creating graphs with independent and dependant variables and finding the slope. It should be something to complicated but also...

-the electrons to the same shell levels of glass as the microwaves pass through and heat the material, or move electrons in a opaque material to the same energy levels, or shell levels of glass, and transparent liquids, and some plastics. In a microwave the waves traverse food, and heat the food...

I'm a bit stuck on this question (which is homework so hints are more welcome than outright answers). The question is: A very long wire carrying a current I is moving with speed v towards a small circular wire loop of radius r. The long wire is in the plane of the loop and is too long to be...

Homework Statement A uniform magnetic field is perpendicular to the plane of a circular loop of diameter 10 cm formed from wire of diameter 2.5 mm and resistivity 8.5×10-8 Ω·m. At what rate must the magnitude of the magnetic field change to induce a 10 A current in the loop? Homework Equations...

Hello everyone, I am beginner in fluent v15, and I want to simulate the temperature change as a function of time in the phase change materials "PCM" and the heat thermal fluid "HTF" and the PCM fusion Front. Regarding the geometry I chose to work with two coaxial tubes: the inner tube contains...

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

In the research paper, a piezoresistive pressure sensor is designed. My question is if we look at table 1 in column 1 the values of deformation of diaphragm for single crystal silicon n type is used If we interchange n type and p type the values for 1000,2000 Kpa are same and then the values...

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...

In the research paper, a piezoresistive pressure sensor is designed. My question is if we look at table 1 in column 1 the values of deformation of diaphragm for single crystal silicon n type is used If we interchange n type and p type the values for 1000,2000 Kpa are same and then the values...

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...

Homework Statement A long, thin solenoid has 400 turns per meter and a radius of 2.65 cm. The current in the solenoid is increasing at a uniform rate dI/dt, and the induced electric field at a point near the center of the solenoid and 3.25 cm from its axis is 5.00✕ 10-6 V/m. Calculate dI/dt...

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?