lecture18_tth_2101_S11

lecture18_tth_2101_S11 - PHYS 2101 Spring 2011 1....

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Unformatted text preview: PHYS 2101 Spring 2011 1. Thermodynamic Processes A. Isobaric B. Isochoric C. Isothermal D. Adiabatic 2. Ideal Gas Law PHYS 2101 EX1: Spring 2011 1.0-kg of water at 100° C is converted to steam at 100° C by boiling it at 1 atm. The volume of the water changes from 1 x 10-3 m3 to 1.671 m3 as steam. (a) Whatmuch work is is iagramthe system during this d) c) b) How is the energy done by for this internal energy does the P-V d transferred as heat during the change of the system’s process look process? process? like? during the PHYS 2101 The graph below shows five isotherms (constant temperature). Which isotherm is at the highest temperature? P CT1: Spring 2011 V 1 - Blue 2 - Red 4 - Purple 3 - Green 5 - Orange 6 - All of them are at the same temperature PHYS 2101 For a gas initially in state 1, what happens to the temperature of the gas if it undergoes an isobaric expansion? P CT2: Spring 2011 1 V 1 - The temperature will increase 2 - The temperature will decrease 3 - The temperature will stay the same PHYS 2101 In which of the following processes is the most work done on the gas during a compression? P CT3: Spring 2011 V I sot herm # 1 1 - Isotherm #1 Adiabat # 1 I sot herm # 2 2 - Isotherm #2 3 - Adiabat #1 4 - The work is the same for both isotherms. 5 - The work is the same for all three processes. PHYS 2101 What happens to the temperature of the gas during an adiabatic expansion? P CT4: Spring 2011 V I sot herm # 1 Adiabat # 1 I sot herm # 2 1 - The temperature increases. 2 - The temperature decreases. 3 - The temperature stays the same. PHYS 2101 What happens to the internal energy of the gas during an adiabatic expansion? P CT5: Spring 2011 V I sot herm # 1 Adiabat # 1 I sot herm # 2 1 - The energy increases. 2 - The energy decreases. 3 - The energy stays the same. PHYS 2101 A particular cycle proceeds from A to B to C and back particular At the end of the cycle, what can be saida to A. Along which step(s) of the cycle is there done by work about net energy transfer during transferwork done by the gas?the cycle? he gas?of energy? A B P CT6: Spring 2011 C V The B work is positive. 1 - A to netgained during a complete cycle. Heat is The C work is negative. 2 - B to netlost during a complete cycle. Heat is The A transfer of energy is zero. 3 - C to net work is zero. PHYS 2101 Spring 2011 Thermodynamic Processes and the First Law Process Process Definition Definition What It What It Means Means 1st Law 1 Law Isochoric Isochoric Constant Constant volume volume Wby=0 W =0 ∆ Eint=Q ∆ E =Q Isothermal Isothermal Constant Constant temperature temperature ∆ Eint=0 ∆ E =0 Q=Wby Q=W Adiabatic Adiabatic No heat in or out Q=0 ∆ Eint=-Wby Isobaric Isobaric Constant pressure Graphically simple ∆ Eint=Q-Wby PHYS 2101 CT7: Spring 2011 Answer with all correct answers: A 1 P 2 4 3 1 - Isobaric 2 - Isothermal 3 - Adiabatic 4 - Isochoric 5 - None of them 6 - All of them V Starting from State A, in which process(es) is the the does heat most work donedecrease?gas? gas end the added toup gas? the increase? i emperatureatdone by gas? tnternal workofthe gasthe positive energy thelowest temperature? expand? by PHYS 2101 One mole of ideal gas is initially in State A, where its pressure and volume are (V0,P0). It expands from State A to State B, where its pressure and volume are (3V0,1/2P0). It is then compressed back to its original volume, before being returned to its initial state. A P EX1: Spring 2011 C B V PHYS 2101 EX1: Spring 2011 a) What is the temperature of the gas at State A if P0 = 3 x 105 Pa and V0 = 0.02 m3? b) What is ∆ Eint if the gas taken from State A to State B if P0 = 3 x 105 Pa and V0 = 0.02 m3 and the gas is monatomic? PHYS 2101 EX1: Spring 2011 c) How much heat is added to the gas during this step? d) How much heat is added to the gas during the entire cycle ? PHYS 2101 The figure shows five paths that a monatomic ideal gas could take from State A to another state in the P-V diagram. For which path is ∆ E the greatest? 1 4 2 P CT2: Spring 2011 5 A 3 V 6 - ∆ E is the same along all five paths PHYS 2101 The figure shows five paths that a monatomic ideal gas could take from State A to another state in the P-V diagram. For which path is ∆ E the least? 1 4 2 P CT2: Spring 2011 5 A 3 V 6 - ∆ E is the same along all five paths PHYS 2101 The figure shows five paths that a monatomic ideal gas could take from State A to another state in the P-V diagram. For which paths is ∆ E the same? 1 4 2 P CT2: Spring 2011 5 A 3 V 6 - ∆ E is the same along all five paths PHYS 2101 The figure shows five paths that a monatomic ideal gas could take from State A to another state in the P-V diagram. Is the amount of energy added to the system as heat the same along paths 1 and 5? 1 4 2 P CT2: Spring 2011 5 A 3 V 1 - Yes 2 - No ...
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