Energy & Heat Transfer
1 / 50
Mayer’s relation for ideal gases is:
Explanation: Mayer’s relation shows cp exceeds cv by the gas constant due to work. It’s derived from the First Law for ideal gases.
2 / 50
The unit of specific heat is
Explanation: Specific heat measures heat per unit mass per degree, hence J/kg·K. Other units apply to energy, heat capacity, or pressure.
3 / 50
For an ideal gas, cv depends primarily on:
Explanation: cv for ideal gases is constant or varies with temperature, affecting internal energy. Pressure, volume, or entropy don’t directly govern it.
4 / 50
In an isobaric process, heat added relates to:
 Explanation: Heat at constant pressure increases enthalpy (Q = ΔH = m·cp·ΔT). Internal energy changes partially, with work involved.
5 / 50
Specific heat at constant volume is critical in:
Explanation: cv applies to constant-volume systems like rigid tanks, affecting internal energy. Turbines and nozzles involve flow and cp.
6 / 50
cp is higher than cv because:
 Explanation: cp includes heat for expansion work plus internal energy, unlike cv. This extra work makes cp > cv for ideal gases.
7 / 50
In a constant volume process, heat added equals:
 Explanation: With no work (W = 0), heat increases internal energy (Q = ΔU = m·cv·ΔT). Enthalpy and pressure changes are secondary.
8 / 50
For ideal gases, the relation between cp and cv is:
Explanation: cp exceeds cv by the gas constant R, accounting for PV work. This is Mayer’s relation, key for ideal gas problems.
9 / 50
Specific heat at constant pressure (cp) is used for:
Explanation: cp governs heat addition at constant pressure, affecting enthalpy (ΔH = m·cp·ΔT). Other processes use cv or involve no heat.
10 / 50
Specific heat at constant volume (cv) relates to:
 Explanation: At constant volume, heat increases internal energy (ΔU = m·cv·ΔT). Enthalpy, pressure, or entropy changes involve other processes.
11 / 50
The First Law for open systems emphasizes:
Explanation: Open system energy balance uses enthalpy to account for flow work. Internal energy is key in closed systems; entropy and volume are secondary.
12 / 50
Flow work is significant in which device?
Explanation: Compressors involve flow work as fluid is pushed in/out under pressure. Piston-cylinders and rigid tanks are closed; isolated systems have no work.
13 / 50
In a nozzle, the energy balance typically increases:
Explanation: Nozzles convert enthalpy into kinetic energy, accelerating fluid with no shaft work. Potential energy and enthalpy changes are secondary.
14 / 50
The energy balance equation accounts for:
Explanation: The steady-flow equation includes enthalpy (with flow work), kinetic, and potential energy terms. Heat and work are inputs/outputs, not stored energies.
15 / 50
Flow work is zero in:
Explanation: Closed systems have no mass flow, so flow work doesn’t occur. Pumps, nozzles, and turbines involve flow work due to fluid movement.
16 / 50
In a turbine, the energy balance primarily involves:
Explanation: Turbines convert fluid enthalpy into shaft work, often with negligible heat transfer. Potential energy and internal energy are less dominant in steady flow.
17 / 50
The steady-flow energy equation applies to:
Explanation: The steady-flow equation balances energy in systems with mass flow, like nozzles. Closed or isolated systems use different First Law forms.
18 / 50
Enthalpy includes:
 Enthalpy combines internal energy and flow work. Kinetic energy is separate in energy balance equations.
19 / 50
Flow work per unit mass is:
Explanation: Flow work is pressure times specific volume, pushing fluid across boundaries. It’s part of enthalpy, distinct from internal energy or heat/work terms.
20 / 50
Flow work is associated with:
Explanation: Flow work occurs when fluid enters or exits an open system, like a turbine. Closed, isolated, or rigid systems don’t involve mass flow.
21 / 50
Shaft work is measured by:
Explanation: Shaft work involves torque applied over angular displacement in rotating systems. Other options relate to PV work, electrical work, or heat.
22 / 50
PV work in an isobaric process depends on:
Explanation: In constant-pressure (isobaric) processes, PV work is , driven by volume change. Other options relate to different work types or processes.
23 / 50
Negative electrical work indicates
Explanation: Negative electrical work occurs when the system (e.g., motor) receives electrical energy. Positive work is done by systems like generators; heat is separate.
24 / 50
In the First Law, PV work affects:
Explanation: PV work in closed systems changes internal energy via . Enthalpy is key in open systems; entropy and temperature are secondary effects.
25 / 50
Electrical work is significant in:
Explanation: Electric motors convert electrical energy to work via voltage and current. Other devices primarily involve PV work, shaft work, or heat transfer.
26 / 50
Positive shaft work occurs in:
Explanation: Turbines produce shaft work by rotating blades, doing work on surroundings. Pumps and compressors require work input; heat exchangers focus on heat.
27 / 50
PV work is zero in a:
Explanation: No volume change in a rigid container means no PV work. Other processes involve work if volume changes occur.
28 / 50
Electrical work involves:
Explanation: Electrical work is driven by voltage and current, as in motors or generators. PV work, shaft work, and heat are distinct energy transfer mechanisms.
29 / 50
Shaft work is most relevant in:
Explanation: Shaft work, like in turbines or pumps, involves energy transfer in flow systems. Closed systems prioritize PV work; isolated systems have no work.
30 / 50
PV work is associated with:
Explanation: PV work occurs when a system’s volume changes under pressure, like gas expanding in a piston. Other options relate to shaft work (rotation) or electrical work (current).
31 / 50
In a free expansion process:
 Explanation: Free expansion into a vacuum has no heat (insulated) or work (no resistance). For ideal gases, internal energy stays constant as temperature doesn’t change.
32 / 50
Work transfer is significant in:
 Explanation: Open systems like turbines produce work via mass flow and boundary motion. Isolated or boundary-less systems don’t facilitate work; entropy defines isentropic processes.
33 / 50
Heat transfer is most critical in which device?
 Explanation: Heat exchangers transfer heat between fluids, like steam to water in power plants. Compressors, turbines, and pistons prioritize work over heat transfer.
34 / 50
The First Law of Thermodynamics involves:
 Explanation: The First Law states internal energy increases with heat added, decreases with work done. Other options misrepresent this energy balance for closed systems.
35 / 50
Positive work transfer indicates:
 Explanation: Positive work occurs when the system expands, pushing its surroundings. Negative work or heat transfers are distinct, per GATE’s sign convention.
36 / 50
Pressure-volume work is zero in:
 Explanation: No volume change in a rigid container means no pressure-volume work. Other processes like isobaric or isothermal involve work if volume changes.
37 / 50
In an adiabatic process:
 Explanation: Adiabatic processes have no heat transfer due to insulation or speed. Work or internal energy changes can still occur, unlike in isothermal or zero-temperature cases.
38 / 50
Heat is a:
Explanation: Heat depends on the process path, varying in constant-pressure vs. constant-volume heating. Unlike state functions (e.g., internal energy), it’s not fixed by system state.
39 / 50
Work transfer in thermodynamics is primarily associated with:
 Explanation: Work involves boundary movement, like a gas pushing a piston during expansion. Molecular energy, heat, or temperature changes are distinct from mechanical work transfer.
40 / 50
Heat transfer occurs due to:
Explanation: Heat flows from higher to lower temperature, like a hot mug warming cold air. Pressure, volume, or entropy changes relate to work or process outcomes, not heat’s cause.
41 / 50
In an ideal gas isothermal process, internal energy:
42 / 50
Specific heat at constant pressure (cp) governs:
43 / 50
Enthalpy is critical in turbines because it:
44 / 50
In a constant volume process, ΔU equals:
45 / 50
For an ideal gas, specific enthalpy relates to internal energy by
 Explanation: Since P⋅v=R⋅T, enthalpy is h=u+R⋅T
46 / 50
Enthalpy is most relevant in:
 Explanation: Enthalpy is key for flow processes like turbines.
47 / 50
Enthalpy is defined as:
 Explanation: Enthalpy includes internal energy and flow work.
48 / 50
The First Law relates internal energy to:
 Explanation: Change in internal energy equals heat added minus work done by the system.
49 / 50
For an ideal gas, internal energy depends on:
 Explanation: Ideal gas internal energy is a function of temperature only ( u=cv​⋅T).
50 / 50
What does internal energy of a system represent?
Explanation: Internal energy ( U) is the sum of molecular kinetic and potential energies.
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