Thermodynamics: Class 11 Physics Q&A
37 free answers on Thermodynamics (Physics) for Class 11 students, across CBSE, ICSE and State boards. Includes questions such as “What is temperature?”, “Main differences between reversible and irreversible processes.”, “what is the isothermal process?”
Question & Answer
Questions
- PhysicsClass 11CBSE
What is temperature?
Temperature measures the average kinetic energy of particles (atoms or molecules) in a substance in other words, how fast the particles inside something are moving or vibrating.When you heat a substance, particles get more energy and move faster. Temperature captures that average speed.Three main scales:Celsius: water freezes at 0, boils at 100 used worldwide in daily life<li
- PhysicsClass 11All
Main differences between reversible and irreversible processes.
In the context of thermodynamics, reversible and irreversible processes refer to different types of transformations that a system can undergo. Here are five main differences between reversible and irreversible processes: Direction of the Process: Reversible Process: In a reversible process, the system undergoes a series of changes in such a way that, at every step, the system and its surroundings can be brought back to their original states without leaving any trace. Essential
- PhysicsClass 11All
what is the isothermal process?
An isothermal process is a thermodynamic process in which the temperature of a system remains constant throughout the entire process. In other words, during an isothermal process, the system does not experience any change in temperature. This is typically achieved by maintaining the system in thermal equilibrium with its surroundings, which means that heat is added to or removed from the system to counteract any temperature changes caused by the process. Key characteristics and concep
- PhysicsClass 11All
what is the latent heat of fusion?
The latent heat of fusion, often simply referred to as the "heat of fusion," is a thermodynamic concept related to the phase transition of a substance from a solid to a liquid state. It represents the amount of heat energy required to change one unit of mass (typically one gram or one kilogram) of a substance from a solid at its melting point to a liquid at the same temperature, without changing the temperature. The heat of fusion is typically expressed in units of energy per unit mas
- PhysicsClass 11All
In a thermodynamic process, 400 J of heat is given to a gas and 100 J of work is also done on it. What is the change in the internal energy of the gas?
ΔU = 400 – (–100) J = 500 J
- PhysicsClass 11All
How to use the formula q = mcΔt?
To use this heat transfer formula: Identify the mass (m) of the substance Find specific heat capacity (c) from tables Calculate temperature change: Δt = t_final - t_initial Multiply: q = m × c × Δt Example: Heat 100g of water from 20°C to 80°C (c = 4.18 J/g°C): q = 100 × 4.18 × (80-20) = 25,080 J
- PhysicsClass 11All
What formula is q = mcΔt?
This is the heat transfer formula: q = heat energy transferred (joules) m = mass of substance (kg or g) c = specific heat capacity (J/kg·K or J/g·°C) Δt = temperature change (K or °C) This calculates energy required to change a substance's temperature. Not directly work, but related through the first law of thermodynamics.
- PhysicsClass 11All
What are types of work in physics?
Physics recognizes several work categories: Mechanical work: W = F × d Thermodynamic work: W = -PΔV (pressure-volume work) Electrical work: W = qV (charge times voltage) Gravitational work: W = mgh Spring work: W = ½kx² Rotational work: W = τθ (torque times angular displacement)
- PhysicsClass 11All
Why is W = -PV?
The complete form is W = -PΔV. The negative sign is a sign convention: When gas expands (ΔV positive): System does work on surroundings (W positive) When gas compresses (ΔV negative): Surroundings do work on system (W negative) This convention ensures thermodynamic consistency with the first law: ΔU = Q - W.
- PhysicsClass 11All
What is the meaning of W = -PΔV?
This formula represents thermodynamic work in gas processes: W = work done by or on the gas P = pressure (constant for isobaric processes) ΔV = change in volume (V_final - V_initial) Negative sign: Convention where work done BY the system is positive When gas expands (ΔV > 0), work is done by the gas (positive). When compressed (&Delt
- PhysicsClass 11All
What is 373 K to °C?
373 K (or more precisely 373.15 K) equals 100°C. This is the boiling point of water at standard atmospheric pressure.
- PhysicsClass 11All
How Cv = f/2R?
For an ideal gas, Cv = (f/2)R, where: f = degrees of freedom (ways molecules can store energy) R = universal gas constant (8.314 J/mol·K) For example: Monatomic gases (f=3): Cv = 3R/2 Diatomic gases (f=5): Cv = 5R/2 This relates molecular motion to heat capacity.
- PhysicsClass 11All
What is Cv chemistry?
In chemistry, Cv is the molar heat capacity at constant volume the amount of energy needed to raise 1 mole of a substance by 1°C when volume is held constant. It's particularly important for gases and thermodynamic calculations, typically measured in J/(mol·K).
- PhysicsClass 11All
What are the 4 units of heat?
The four common units for measuring heat energy are: Joule (J) - SI unit, standard in science Calorie (cal) - energy to raise 1g of water by 1°C; 1 cal = 4.184 J Kilocalorie (kcal or Cal) - dietary "Calorie"; 1 kcal = 1000 cal British Thermal Unit (BTU) - energy to raise 1 lb of water by 1°F; used in HVAC Joules are preferred in scientific work, while BTUs r
- PhysicsClass 11All
Is 98.6°F the same as 37.4°C?
Almost 98.6°F actually euals 37.0°C (not 37.4°C). The 98.6°F figure is the traditional "normal" body temperature, though modern research shows normal temperature varies between individuals and throughout the day, typically ranging from 97°F to 99°F (36.1°C to 37.2°C).
- PhysicsClass 11All
What is CP and CV?
Cp and Cv are heat capacities at constant pressure and constant volume: Cp (constant pressure) - heat capacity when pressure stays constant; usually larger Cv (constant volume) - heat capacity when volume stays constant; usually smaller For ideal gases, the relationship is Cp - Cv = R (gas constant). Cp is always greater because energy is needed both to raise temperature and to do expansion work against constant pressu
- PhysicsClass 11All
What is heat capacity?
Heat capacity is the amount of heat energy reuired to raise the temperature of an object or substance by 1°C (or 1 K). It's measured in J/°C or J/K. Heat capacity depends on both the material and the amount—more mass means higher heat capacity. Specific heat capacity is the heat capacity per unit mass.
- PhysicsClass 11All
What is C in = mcΔt?
c (lowercase) represents specific heat capacity the amount of energy reuired to raise the temperature of 1 gram (or 1 kg) of a substance by 1°C. Different materials have different specific heat capacities: Water: 4.18 J/g°C (very high) Iron: 0.45 J/g°C Copper: 0.39 J/g°C Water's high specific heat capacity makes it excellent for temperature regulation.
- PhysicsClass 11All
Is eual to C Delta T?
Almost the complete formula is = mcΔT. You can also write it as = CΔT, where capital C represents the total heat capacity (C = mc), combining mass and specific heat capacity into one value. This simplified version is useful when dealing with objects of known total heat capacity.
- PhysicsClass 11All
What does mc ∆t stand for?
In the euation = mcΔt: = heat energy transferred (joules or calories) m = mass of the substance c = specific heat capacity (amount of energy needed to raise 1 gram by 1°C) Δt = change in temperature This euation calculates the thermal energy reuired to change a substance's temperature without changing its state.