PH101 HW Thermodynamics

# PH101 HW Thermodynamics - This print-out should have 25...

This preview shows pages 1–3. Sign up to view the full content.

This print-out should have 25 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 (part 1 oF 3) 10.0 points Two glasses oF water contain di±erent volumes oF water at the same temperature. A B In which glass are the water molecules mov- ing Faster? 1. B 2. Same speed in both correct 3. Unable to determine 4. A Explanation: The temperatures are the same, so the molecules have the same average speed. 002 (part 2 oF 3) 10.0 points Which glass contains more thermal energy? 1. A correct 2. Unable to determine 3. Same in both 4. B Explanation: Equal speeds means equal kinetic energy. Acon ta in smo r emo l e cu l e s ,soAha r e thermal energy. 003 (part 3 oF 3) 10.0 points Which glass requires more heat to increase its temperature by 1 C? 1. Either 2. B 3. A correct 4. Unable to determine Explanation: remo lecu le s ,soi trequ i re s more heat to increase its temperature. 004 10.0 points Aworkerdrivesa0.462kgspikeintoarailtie with a 2.09 kg sledgehammer. The hammer hits the spike with a speed oF 64.1 m/s. IF one Fourth oF the hammer’s kinetic en- ergy is converted to the internal energy oF the hammer and spike, how much does the total internal energy increase? Correct answer: 1072 . 4J. Explanation: Let : m s =0 . 462 kg m h =2 . 09 kg v h =64 . 1m / s Δ U = 1 4 K = 1 4 ± 1 2 m h v 2 h ² = 1 8 m h v 2 h = 1 8 (2 . 088 kg) (64 . / s) 2 = 1072 . 4J . 005 10.0 points Ac o n t a i n e ro Fv o l um e0 . 87 m 3 contains 4 . 9moloFargongasat50 C. Assuming argon behaves as an ideal gas, fnd the total internal energy oF this gas. The value oF gas constant is 8 . 31451 J / mol · K. Correct answer: 19739 . 1J. Explanation:

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Let : V =0 . 87 m 3 , T =50 C=323K , and n =4 . 9mol . The number of molecules in the gas is N = nN A ,sothetota lenergyis U = NK av = a ± 3 2 k B T ² = 3 2 nRT = 3 2 (4 . 9mol)(8 . 31451 J / mol · K) (323 K) = 19739 . 1J . 006 10.0 points What is the Fnal equilibrium temperature when 18 g of milk at 28 Cisaddedto163gof co±ee at 74 C? Assume the speciFc heats of milk and co±ee are the same as that of water, and neglect the speciFc heat of the container. Correct answer: 69 . 4254 C. Explanation: Let : m m =18g , T m =28 C , m c =163g , and T c =74 C . The amount of heat given out by co±ee should be equal to the amount of heat ab- sorbed by milk, so c m m m ( T f - T m )= c c m c ( T c - T f ) m m T f - m m T m = m c T c - m c T f ( m m + m c ) T f = m c T c + m m T m T f = m c T c + m m T m m m + m c = (163 g) (74 C) + (18 g) (28 C) 18 g + 163 g = 69 . 4254 C .
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 10/03/2010 for the course PH 101 taught by Professor Jones,s during the Spring '08 term at Alabama.

### Page1 / 7

PH101 HW Thermodynamics - This print-out should have 25...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online