Internal energy Definition and 381 Threads

I'm currently studying A2 physics and I'm stumped on a particular question within a past paper involving internal energy of air. The question is as follows: Estimate the internal energy of the air in a room of volume 24m^3 at a temperature of about 20˚C. Assume that the air behaves as an...

Homework Statement The problem is that there are two , two-state paramagnets with Na = Nb (number of dipoles in each). uB = |kT|, energies of each dipole are + or - uB. Different internal energies to start, but they are brought together at thermal equilibrium and I need to find the average...

Can anyone tell me if Internal\ Energy + Pressure * Volume equals heat, total energy, energy in transit? What if all energy is assumed to be in transit (heat all the way down)? Would that mean all energy is heat? I tend to think so for the following reason: In a "complete" system (with...

ok so DELTA U = Q - W Where U is internal energy, Q is heat transferred from or to the system and W is the work done BY the gas right? I always mix up U and Q, the concepts. My teacher said U depends entirely on temperature, is this right?? Also, if Q =ncDELTA T, isn't Q also dependent on...

Ok, I must admit that I am becoming a bit confused about these concepts. I understand that enthalpy is u + Pv, and entropy has something to do with molecular randomness. I was fine until we started to solve for heat transfer when dealing with entropy and now I am confused, sometimes we use...

I need a little starter on this one...can't figure out how to do it(or even start it)...I'll work it, if I can get some help along the way... Two moles of an ideal gas at 20 deg C undergo a free adiabatic expansion from 2.0 liters to 66 liters. Then the gas is adiabatically compressed such...

Sir, I have a doubt. The internal energy U is a unique function of any state because change in U ___________. I think the answer is internal energy U is a unique function of any state because change in U does not depend upon path.U is a point function. But the given in book is " U depends...

Hi I wanted to know : - Most gases increase in temperature when they are compressed . Where does the energy for this come from . When a change of state from liquid to gases occurs is it accompanied by change in the internal energy of the liquid molecules ? Thanks a lot ..

Hi all, I'm stuck on a question, and I'm hoping you guys can help... Anyway, here it is: A J-shock in a Herbig-Haro object is propagating through neutral hydrogen gas at speed 100 kms-1. The gas has number density 107 m-3 and temperature 104 K. (d) The internal energy per unit mass of a...

A worker drives .5 kg spike into a rail tie with 2.50 kg hammer. Hits spike with 65 m/s. 1/3 kinetic energy converted to internal energy. Find increase in total internal energy. The problem I have having with this problem is that I don't know how to deal with the masses. I know PEi + KEi +...

hello I just realized I'm having some trouble figuring out the relationship between conservation of momentum and kinetic energy and internal energy in isolated system. We learned that total momentum gets conserved if two object collide in isolated system. But when learning about...

1. Cylinder contains 0.1 mol of ideal gas at a pressure of 2 atm and temperature of 300 K. The volume of the cylinder is 1.25 x 10^-3 m3. When the gas is heated from 300K to 350K, what is the change in internal energy of the gas? --->(I think the equation is Q=delta U + W but I don't know...

hello How does macroscopic kinetic energy KE get transformed into internal energy? Car bumps into trash can and small dent is made in the car.Dent is caused by force from trash can over certain distance (i.e. car gave part of its KE to trash can and trash can gave part of its KE back to...

hello First question-Internal energy W(I) of an ideal gas consists only of internal kinetic energy (thermal energy) W(KE). W(I) = W(KE) If at temperature T there are N molecules in an ideal gas,then total W(I) is W(I) = N*3/2*k*T We see from above formula that W(I) of ideal gas...

i figured out that Wac=21000J Wbc=0 Wab=91000J how do you find internal energy of U=Q+W?

Q) A 3 g bullet traveling at a speed of 400m/s enters a tree and exits the other side with a speed of 200 m/s. Where did the bullet's lost KE go, and what was the energy transferred? This is an example prob from my book which says: Change in KE+Change in Internal Energy=0 Hence, Change in...

alright, so I'm reviewing for a test I have on monday, and I was given a study guide which we must answer in order to get ready for the test. Now I just breeze through this stuff like its nothing, but I've found on discrepency. I even looked up the question online and i got 2 completely...

930.J of work are done by an insulated system that absorbs 3.35Kcal of heat. What is the change in the internal energy of the system? Ok so I don't quite understand this. I know that U=Q-W. but I do I just do 3.35Kcal minus W? This just doesn't seem right.

A cylinder contains 0.0100 mol of helium at T = 27.0 ^\circ \text{C}. If the presure of the helium is kept constant, how much heat is needed to raise the temperature from 27.0 to 67.0 C? If the gas is ideal, what is the change in its internal energy? I got the answer for the first part...

Question: When a quantity of monatomic ideal gas expands at a constant pressure of 4.00 \times 10^{4} {\rm Pa}, the volume of the gas increases from 2.00 \times 10^{ - 3} {\rm m}^{3} to 8.00 \times 10^{ - 3} {\rm m}^{3}. A. What is the change in the internal energy of the gas? It's isobaric...

I figured there must be a relationship between internal energy and enthalpy after doing this physics question sheet which seemed to suggest this because there was a graph (pressure-volume) showing 2 routes to same finial condition...which reminded me of la chatelier's principle (think that's the...

A tank of volume 0.413 m3 contains 2.79 mol of helium gas at 5C. Assume that the helium behaves like as an ideal gas. The universal gas constant is 8.31451 J/Kmol, and Boltzmann's constant is 1.38066 x10^-23 J/K. Find the total thermal energy of the system. Answer in units of J. Would...

A cylinder (cross section is 0.2m2) with a free moving piston is filled with gas. The piston is attached to a heavy weight W = 10000N. Outside the cylinder, the air is at 300K and 1atm. Initially the gas is at 300K, then it is heated to 400K. The heat capacity of the gas under the constant...

In moving out of a dormitory at the end of the semester, a student does 2.69 x 104 J of work. In the process, his internal energy decreases by 5.52 x 104 J. Determine each of the following quantities (including the algebraic sign): (a)W, (b) delta U, and (c)Q. I get the following using...

This Q has me stumped, I'm still flicking through some web pages and my textbook, but been unable to find a useful formula to work it out yet: :confused:

I do not know what to solve for...? One recargable battery of mass 15g delivers to a cd player an average current of 1.80mA at 1.60 V for 2.4hours before the battery needs to be recharged. The recharger maintains a potential difference of 2.30v across the battery and delivers a charging...

>> An ideal gas is compressed to one-fourth of its original volume while its temperature is held constant. (Hint: solve part (b) first.) (a) If 950 J of energy is removed from the gas during the compression, how much work is done on the gas? (b) What is the change in the internal energy of the...

I have a question concerning internal energy and the First Law of Thermodynamics. If you plotted P vs V and the shape of the graph is an enclosed shape ie) square or triangle, would the total internal energy in one cycle be zero? (one cycle is for example-start at top left of square and finish...

I've got a set of questions based on internal energy and specific heat capacities and things. I could just do with a bit of help on some of them. Just a push in the right direction will probably do! Thanks. Specific heat capacity of water = 4200 J/kg/K Specific heat capacity of ice = 2100...

Determine the change in internal energy of 1 kg of water at 100 degrees C when it is fully boiled. Once boiled this volume of water changes to 1671 Liters of steam at 100 degrees C Assume the pressure remains constantat 1 atm things i know 1 L =1E-3 m3 1atm = 1.013E5 N/m2 1 L = 1000 cm3 =...

Seem to have ran into a brick wall with this problem Determine the change in internal energy of 1 kg of water at 100 degrees C when it is fully boiled. Once boiled this volume of water changes to 1671 Liters of steam at 100 degrees C Assume the pressure remains constantat 1 atm things i know...