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What is the ratio T f / T i for this process?

What is the ratio T f / T i for this process?. 4 2 1 (no change). What is the ratio T f / T i for this process?. 4 2 1 (no change).

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What is the ratio T f / T i for this process?

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  1. What is the ratio Tf /Ti for this process? • 4 • 2 • 1 (no change)

  2. What is the ratio Tf /Ti for this process? • 4 • 2 • 1 (no change)

  3. A gas cylinder and piston are covered with heavy insulation. The piston is pushed into the cylinder, compressing the gas. In this process, the gas temperature • doesn’t change. • decreases. • increases. • there’s not sufficient information to tell.

  4. A gas cylinder and piston are covered with heavy insulation. The piston is pushed into the cylinder, compressing the gas. In this process, the gas temperature • doesn’t change. • decreases. • increases. • there’s not sufficient information to tell.

  5. Two process are shown that take an ideal gas from state 1 to state 3. Compare the work done by process A to the work done by process B. • WA = WB = 0 • WA > WB • WA = WB but neither is zero • WA < WB

  6. Two process are shown that take an ideal gas from state 1 to state 3. Compare the work done by process A to the work done by process B. • WA = WB = 0 • WA > WB • WA = WB but neither is zero • WA < WB

  7. Which of the following processes involve heat? • The brakes in your car get hot when you stop. • A steel block is placed under a candle. • You push a rigid cylinder of gas across a frictionless surface. • You push a piston into a cylinder of gas, increasing the temperature of the gas. • A gas-filled, uninsulated cylinder is immersed in ice water. The piston is covered with pellets that you slowly remove. The gas expands, causing the piston to rise. The temperature of the gas remains at 0°C.

  8. Which of the following processes involve heat? • The brakes in your car get hot when you stop. • A steel block is placed under a candle. • You push a rigid cylinder of gas across a frictionless surface. • You push a piston into a cylinder of gas, increasing the temperature of the gas. • A gas-filled, uninsulated cylinder is immersed in ice water. The piston is covered with pellets that you slowly remove. The gas expands, causing the piston to rise. The temperature of the gas remains at 0°C. The gas does work on the piston, so it loses energy. The thermal energy must remain the same for the temperature to remain fixed, so there must be heat transfer from the ice water to the gas. There will be an increase in the amount of ice in this process.

  9. Which first-law bar chart describes the process shown in the pV diagram?

  10. Which first-law bar chart describes the process shown in the pV diagram?

  11. For the two processes shown, which of the following is true: • QA < QB. • QA = QB. • QA > QB.

  12. For the two processes shown, which of the following is true: • QA < QB. • QA = QB. • QA > QB.

  13. Which system has the largest average translational kinetic energy per molecule? • 1 mol of He at p = 1 atm, T = 300 K • 2 mol of N2 at p = 0.5 atm, T = 450 K • 2 mol of He at p = 2 atm, T = 300 K • 1 mol of Ar at p = 0.5 atm, T = 450 K • 1 mol of N2 at p = 0.5 atm, T = 600 K

  14. Which system has the largest average translational kinetic energy per molecule? • 1 mol of He at p = 1 atm, T = 300 K • 2 mol of N2 at p = 0.5 atm, T = 450 K • 2 mol of He at p = 2 atm, T = 300 K • 1 mol of Ar at p = 0.5 atm, T = 450 K • 1 mol of N2 at p = 0.5 atm, T = 600 K

  15. What is the thermal efficiency of this heat engine? • 0.10 • 0.25 • 0.50 • 4 • Can’t tell without knowing QC.

  16. What is the thermal efficiency of this heat engine? • 0.10 • 0.25 • 0.50 • 4 • Can’t tell without knowing QC.

  17. What, if anything, is wrong with this refrigerator? • It violates the first law of thermodynamics. • It violates the second law of thermodynamics. • It violates the third law of thermodynamics. • It’s impossible to tell without knowing what kind of cycle it uses. • Nothing is wrong.

  18. What, if anything, is wrong with this refrigerator? • It violates the first law of thermodynamics. • It violates the second law of thermodynamics. • It violates the third law of thermodynamics. • It’s impossible to tell without knowing what kind of cycle it uses. • Nothing is wrong. ΔEth = Q + Win by the first law and ΔEth = 0 for a cycle. We have ΔEth = (40 – 30) + 10 = 20 J for a cycle.

  19. What, if anything, is wrong with this engine cycle? • It violates the first law of thermodynamics. • It violates the second law of thermodynamics. • It violates the third law of thermodynamics. • It’s impossible to tell without knowing what kind of cycle it uses. • Nothing is wrong.

  20. What, if anything, is wrong with this engine cycle? • It violates the first law of thermodynamics. • It violates the second law of thermodynamics. • It violates the third law of thermodynamics. • It’s impossible to tell without knowing what kind of cycle it uses. • Nothing is wrong. One version of the second law states that no cycle operating between a given two temperature extremes can exceed the efficiency of a Carnot cycle operating between the same two temperature extremes. ecarnot = 1 – Tc/Th = 1 – 300/600 = 0.50 and e = W/Qh = 60/100 = 0.60.

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