Recent content by yaylee

Homework Statement Assume the same set-up to measure the stopping potential Vs through different filters. Suppose a filter allowed through only light of frequency fo (the cut-off frequency) or lower. In this case, what would the stopping potential be? 1) you cannot tell, since different...

Homework Statement Suppose the following: the light source gets very hot (by increasing the intensity), what affect do the heated photons have on photoemission? Possible choices: 1) they decrease the number of photoelectrons by heating the metal and raising the work function 2) none...

Homework Statement Suppose a filter allowed through only light of frequency fo (the cut-off frequency) or lower. In this case, what would the stopping potential be? Homework Equations KEmax = (charge of electron)(stopping potential) = hf - Work function, where Work function = hfcutoff...

Homework Statement Which of the following statements about entropy and heat engines are true? (There is more than one right answer!) 1)The entropy of the universe can never decrease 2) The COP (coefficient of performance) of a refrigerator can never be greater than 1 3) All Carnot...

Thanks Gneill! Also, just curious: do you guys help out students (like myself) voluntarily? If so , that is awfully nice !

Homework Statement A microwave oven produces energy at a rate of P = 1219 W, all in the form of microwaves. When a cup of water is placed into this oven, 64.4% of the microwaves are absorbed by the water. If a cup containing mw = 212 grams of water (227 g equals 8 ounces) starts at...

Homework Statement Assume nitrogen gas (N2) is an ideal gas. n = 7.57 moles of N2 gas are heated isobarically (at constant pressure) from temperature To = 18.6 oC to temperature Tf = 50.9 oC. Find: c) ΔIE, the change in internal energy of the N2 gas Homework Equations Change in IE...

Homework Statement n = 1.46 moles of ideal gas are heated isobarically (at constant pressure) from temperature To = 431 oC to temperature Tf = 1227 oC. Find: change in Energy, Q, W. Homework Equations Change in IE = Q + W W (isobaric process) = P(vf-v1) The Attempt at a Solution...

Homework Statement Suppose molten (liquid) lead, mass ml = 9.83 kg, is at its melting point. The lead is poured into water of mass mw = 585 g and initial temperature Tw = 16.2 C. Find mwb, the amount of the water that boils. NOTE: Reaching the boiling point is not enough; the question asks...

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Homework Statement n = 1.46 moles of ideal gas are heated isochorically (at constant volume) from tepmerature To = 649 oC to temperature Tf = 1184 oC. Find: a) Work done on the system. b) Change in Internal Energy of the system. c) The total heat, Q, added or removed from the system...

Ah, OK. There was a mistake with the scoring. Your answer was correct. Thanks for the help!

Hello I like Serena ! Thank you for the welcome. I am sorry for mixing up increase/decrease throughout the problem. In an ideal gas, As temperature DECREASES, Kinetic Energy decreases and therefore internal energy DECREASES. Also: Intermolecular forces are unchanged, or remain...

Homework Statement If the volume V and pressure P of an ideal gas decrease, which statement is true about the internal energy IE, temperature T and the intermolecular forces IF? (I am not going to copy and paste the choices here in an effort to focus attention on the attempt of...

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