pV diagrams, the first law and engine cycles

What is the equation that represents the first law of thermodynamics?

• ΔU = ΔQ + ΔW
• ΔW = ΔQ - ΔU
• ΔQ = ΔU + ΔW
• ΔU = ΔW - ΔQ

What does ΔQ represent in the first law of thermodynamics?

• Internal energy of the system
• Heat supplied to the system
• Work done by the system
• Temperature of the system

What is the increase in internal energy of the system represented by in the first law of thermodynamics?

• ΔQ
• ΔW
• ΔU
• Pressure of the system

When a fixed mass of gas in a cylinder is heated at constant volume, what is the value of ΔW according to the first law of thermodynamics?

• Positive
• Negative
• Zero
• Depends on the initial state of the system

What happens to the internal energy of a system when it expands isothermally according to the first law of thermodynamics?

• Increases
• Decreases
• Remains the same
• Varies with time

What is the unit of pressure?

• Joule
• Meter
• Newton
• Pascal

What is the formula for work done by a gas?

• W = ΔU + Q
• W = ΔU - Q
• W = ΔU * Q
• W = p * ΔV

What is the formula for isothermal process?

• ΔU = Q - W
• ΔU = Q + W
• ΔU = Q / W
• p * V = constant

What is the definition of overall efficiency of a cycle?

• net work output in one cycle / energy supplied by heating from an external source in one cycle
• energy supplied by heating from an external source in one cycle / net work output in one cycle
• net work output in one cycle * energy supplied by heating from an external source in one cycle
• energy supplied by heating from an external source in one cycle - net work output in one cycle

What is the meaning of ΔQ in the first law of thermodynamics equation ΔQ = ΔU + ΔW?

• Decrease in internal energy
• Increase in internal energy
• Heat added (to gas)
• Work done by gas