Internal Definition and 993 Threads

internal energy of a gas :( Hi all! I have a problem with this equation ΔU=mCvΔT, where ΔU=change in internal energy, m=mass, Cv=specific heat of air/gas at constant volume,ΔT=change in temp. Although this expression is true for all processes which can be applied to a gas e.g polytropic...

Hi, Could someone tell me please what is the scientific consensus(or some interesting theories) on why do muons decay and what is the mechanism of it? My understanding of particle decay is based on for example neutron wchich decays because a quark in it flips from down to up. But leptons, if...

2 questions that came up in a past paper. A binary tree which is both full and complete and has h levels contains a total of 2^(h-1) leaf nodes. Prove that this is the case for all h > 0. Show that with h levels the number of internal nodes is 2^(h−1) − 1 proof by induction apparently...

This is in continuation to https://www.physicsforums.com/showthread.php?t=330495 The question that initiated my doubt reads this -- " the internal resistance of an accumulator battery of emf 6V is 10 Ohm when fully discharged . as battery gets charged up , its internal resistance drops to 1...

Hi, I'm looking for a little bit of help in this matter, I'm trying to put up a general formula of the internal force/volume in a fluid in a spot, as a function of how the velocity varies locally around that spot. What I started with was a formula I found in a book called "Physics Handbook...

I know that phase changes, such as the melting of ice, occur at constant temperature. Doesn't this imply that the change in internal energy during the phase change is zero, since the temperature remains the same? I thought that in all isothermal processes this was the case, so that the First Law...

Homework Statement 1) a complete circuit consists of a 12.0 V battery with a 4.50 ohm resistor and switch. the internal resistance of the battery is 0.30 ohms when switch is open. what does the voltmeter read when placed: a. across the terminal of the battery when the switch is open b...

Does anyone have any experience with liner material for application on pipework with internal corrosion/erosion? Pipes are designed to hold water/methanol vapour Normal operating conditions for the pipes: Temperature • Average temp - 172F • Max temp - 267.1F Pressure • Average...

Does anyone have any experience with liner material for application on pipework with internal corrosion/erosion in a Methanol Regeneration System? There are issues with internal pipe corrosion in a Methanol processing systems I am dealing with. To alleviate the current high rates it has...

Homework Statement A 24 voltt supply has a terminal voltage of 20 volts when connected to a 40R Load Resistor. Calculate the internal resistance of the supply State the conditions under which maximum power will be transferred to load. Homework Equations V = E - Ir V = p.d...

A steam engine of 1kg pulls 8 cars of 1kg each. The velocity of the engine is 0m/s initially then gets up to 4m/s in a time of 4 s while moving a distance of 5.3 meters. During that time, the engine takes in 134J of heat. What is the change in internal energy? Ok so i know that: internal...

ISP can tell what my internal network ip's are? To make a long story short, I use a router, with two computers behind it, I called my ISP for technical help, and the technician there told me I use a router (which is a reason for him to not help me..). He said he sees more then one IP address...

Homework Statement A resistor has a resistance R, and a battery has an internal resistance r. When the resistor is connected across the battery, ten percent less power is dissipated in R than there would be if the battery had no internal resistance. Find the ratio r/R Homework Equations...

Homework Statement The internal energy of a monoatomic ideal gas such as neon is simply the total kinetic energy of all its atoms. What is the internal energy of 2 liters of neon at a temperature of 200 K and pressure of 0.7 atm? Homework Equations PV = nRT KE(ave) = 3/2kT U =...

Hi guys, I am hoping some one can help me out here and after some forumlas and very basic ones at that on internal ballistics. There is a heap of information out there and they tend to jump straight to the hard stuff which tends to be tough on a novice like myself. I have done a heap of...

I am sure someone wrote with great detail on the subject, but i just can't seem to find it in the forums... I want to know about the parameters influencing the performance of an IC engine...obviously, not all parameters, but those we can conviently control specifically...how is bore/stroke...

Homework Statement To find the total internal reflection. This equation should give me 1.48 as the answer but it doesn't. Can you please give me other ways to figure this out. I really need this. Homework Equations n1sin1Ө=n2sin2Ө n1 = 1 n2 =? sin1Ө = 44 degrees sin2Ө = 48 degrees...

Homework Statement I need some help on these problems, i got most of the other problems right, but these ones I am not sure what to do with. I don't even know if those are the right equations for it. Someone please help. 1. A cylinder-and-piston containing an ideal gas is placed in...

Homework Statement Suppose a terrorist bomb has exploded next to a friend and injured him by opening two small openings in his chest wall: one on the left side, one on the right side (assume that no significant internal bleeding has occured). Can you suggest, and explain, the purpose of an...

Dear Everyone I am facing the following engineering problem. I "inject" light in a flat (6.5mm) Acrylic panel at the edges of it. Due the different refractive index of the Acrylic material (1.4) and air (1) 90% of the "injected light" experiments total internal reflexion. I need to get the...

When taking internal resistance into account, voltage/current graph has negative gradient (i.e. internal resistance).? My thoughts... Because for ohmic resistors, graph has a positive gradient. Why does one say that when V=0, Current = max, whilst the other says that when V=0, Current = 0?

The name "phantom limb" implies an external extension of the body. Has a similar phenomenon been reported for internal organs? Thanks for any and all.

Homework Statement Hi everyone. I am attempting to calculate the internal moment at point B about the y-axis. I have correctly found everything else. My calculations: Weight of 500mm section of pipe = 58.9N Weight of 400mm section of pipe = 47.1N Vertical reaction at A = 58.9 + 47.1 = 106N...

Homework Statement A 5.60ohm resistor is connected to a battery that has 0.200ohm internal resistance, and a terminal voltage of the battery is 10.0V. What is the current in the resistor? What is the emf of the battery? Homework Equations EMF=terminal voltage+(I)(Rint.) V=RI The...

I'm trying to determine the forces that an internal gear applies on a pinion. I can measure the angular velocity of the gear and any relevant dimensions but can only find force equations for gears with a single point of contact. Any guidance is greatly appreciated.

Homework Statement Please help, I've been struggling with this question for so long! We haven't done internal energy so I am not sure even where to really begin? A 10.0 kg block is dragged over a rough, horizontal surface by a 76.0 N force acting at 20.0° above the horizontal. The block...

Homework Statement The prism is replaced by a new prism of the same shape, which is set in the same position. The light beam experiences total internal reflection at the right surface of this prism. What is the minimum possible index of refraction of this prism? Homework Equations...

Can i ask sth? Why centripetal accel is from an internal force? Usually what type of forces can be considered as external force, besides friction? And, for static equilibrium, do we only use the eqn: sum of forces equals zero, or we can also apply sum of moments equals zero? Thanks!

Hi, I am going to teach a class of year 9 students on the topic "Thermal Properties of Matter" and the concept of Internal Energy is mentioned inside. As I was trying to anticipate the types of questions that will be asked by them, this question suddenly struck me: Is there a limit to the...

Homework Statement Tarzan, whose mass is 110 kg, is hanging at rest from a tree limb. Then he let's go and falls to the ground. Just before he let's go, his center of mass is at a height 3.0 m above the ground and the bottom of his dangling feet are at a height 2.0 above the ground. When he...

i have attached a past paper question on internal forces and stress-strain, please help!

Homework Statement Light is incident normally on the short face of a 30-60-90 (degree) prism. A drop of liquid is placed on the hypotenuse of the prism.If the index of the prism is 1.68, find the maximum index that the liquid may have if the light is to be totally reflected. Homework Equations...

If a cell is connected with an external resistor of 6V and a switch and a voltmeter is connected across the terminals of the cell which reads 2.6 V when the switch is open and 2.4 V when the switch is closed, how do you find the emf and the internal resistance? so far i tried doing: V = IR...

The task is to derive an expression for the heat capacity of a system at constant volume and show that at high temperatures it is inversely proportional to the square of temperature. As far as I'm concerned the relation between internal energy and heat capacity is: Cv=dE/dT However with...

Why does total internal reflection happen in glass?

Homework Statement A gas sample heated in a cylinder used 650 kJ of heat. A piston that compresses the gas does 800 kJ of work. What is the change in internal energy, ΔE, of the gas during this process Homework Equations ΔE = q + w The Attempt at a Solution ΔE = q + w ΔE =...

Hmm. This is another thing I'm unsure abt. When some mechanical energy is converted to internal energy, can we still say that energy is conserved? Can the internal energy be negative? Thanks for answering my qns :)

Homework Statement I performed a lab where we designed an electric circuit on paper and then calculated the Current, Power, and Voltage for each of the resistors. We used one power supply. Then we built the circuit we designed and then measured the actual Current Power and Voltage for the it...

Hi all, I am new to this forum and COMSOL. I want to define the temperature at the common surface of two cylinders in contact. When I model the cylinders, the common surface (middle surface) is not active for defining any BC. Please tell me how can I do this in COMSOL. Thanks.

A cup of water is scooped up from a swimming pool of water. Compare the temperature T and the internal energy U of the water, in both the cup and the swimming pool. a) Tpool is less than Tcup, and the U is the same. b) Tpool is equal to Tcup, and Upool is less than Ucup. c) Tpool is equal to...

How do you combine two separate volumes of an ideal gas which are at different temperatures pressures and volumes and then work out the change in internal energy? I have been trying to get my head around this without success.

Ok, I know this question is very old, and it has probably been answered by now, but if the electron does not have an internal structure (like the proton for example), how does it maintain itself as an entity? Why does it not disintegrate? I've asked this question a couple of times before ,and...

Consider two adjacent transparent media. The speed of light through Medium 1 is v1, and the speed of light through Medium 2 is v2. If v1<v2, then total internal reflection will occur at the interface between these media if a beam of light is? I said incident in Medium 1 and stikes the...

I was searching a clip in Youtube and got: Is this really funny?

Consider a gas contained in volume V at temperature T. The gas is composed of N distinguishable particles at zero rest mass, so that the energy E and momentum p are related by E = pc. The number of single-particle energy states in the range p to p + dp is 4\pi Vp^2 dp . Find the equation of...

I note that in many case, we always use the constant-volume specific heat to calculate the change of internal energy. For example, in a adiabatic process (P1, V1, T1) to (P2, V2, T2), since internal energy is state variable, we always like to build a fictitious isochoric process from (P1...

Hello, while studying thermodynamics I was wondering why, in a system where the pression is not univocally determined (for example in irreversible trasformations), to measure the total work of the trasformation, we use to consider only the external forces. I mean, this sounds conceptually right...

Hello, I know that something around 65% of the potential energy stored in fuel is lossed in an engine through heat. I am trying to find exactly how its lossed, I know some is through piston friction, and some is lossed through the exhost, but I can't find how much is lossed for each...

If I set up a coil with thin wire, push a magnet through it, and connect either end to a voltmeter (in series), then is this an accurate way to measure the total voltage? I might not be phrasing this right, so ask me to clarify if I should. I'm guessing that you can't just simplify a circuit...

PROBLEM: Some warm water is mixed with ice and the ice melts. Assume that the entire process happens in an insulated box. Does the internal energy of the combined (ice+water) system change? Does the entropy of the combined system change? Considering that the ice and water as separate...