Question

Amount of heat required to raise the temperature of a body through \(1 \mathrm{k}\) is called it is (A) Water equivalent (B) Thermal capacity (C) Entropy (D) Specific heat

Short answer

The correct answer is (D) Specific Heat, as it is the amount of heat energy required to raise the temperature of a unit mass of a substance by 1 Kelvin (or 1 degree Celsius).

Step-by-step solution

A) Water Equivalent

The water equivalent of a body is the mass of water that would absorb or lose the same amount of heat as the body for the same temperature change. The concept of water equivalent is used to compare the thermal behavior of a substance to that of water.

B) Thermal Capacity

Thermal capacity, also known as heat capacity, is the amount of heat needed to change the temperature of an object by 1 degree Celsius or 1 Kelvin. It depends on both the mass and the material of the object. The formula is given by: \[ C = mc \] where `C` is the heat capacity, `m` is the mass, and `c` is the specific heat.

C) Entropy

Entropy is a physical quantity that measures the degree of randomness or disorder within a system. It is related to the concept of energy distribution across particles in the system, and it helps us understand the spontaneous behavior of a thermodynamic system or process.

D) Specific Heat

Specific heat, also known as specific heat capacity, is the amount of heat energy required to raise the temperature of a unit mass of a substance by 1 Kelvin (or 1 degree Celsius). It is a property of the material that makes up an object and varies from one substance to another. The formula for specific heat is given by: \[ q = mcΔT \] where `q` is the heat transferred, `m` is the mass, `c` is the specific heat, and `ΔT` is the change in temperature. Now, as per the given exercise, we need to find the amount of heat required to raise the temperature of a body through 1K. Looking at the above descriptions and formulas, we can determine that the correct answer is: (D) Specific heat

Key concepts

Specific Heat

The concept of specific heat is fundamental in understanding how different materials respond to changes in temperature. Specific heat, sometimes referred to as specific heat capacity, is the measure of heat energy required to raise the temperature of a unit mass of a material by 1 Kelvin (or 1 degree Celsius). This property is specific to the type of material and is expressed in units of \( \text{J/kg·K} \,/\,\text{°C} \).

Specific heat can be determined using the formula:

• \( q = mcΔT \)
where:
• \( q \) is the heat energy transferred,
• \( m \) is the mass of the substance,
• \( c \) is the specific heat,
• \( ΔT \) is the temperature change.

Different materials have different specific heats because molecules in each material respond differently to heat. Water, for example, has a high specific heat, meaning it takes a lot of energy to change its temperature. This is why bodies of water are great at moderating temperature in an environment.

Understanding specific heat is crucial in various scientific and engineering applications, such as designing thermal systems or predicting the ecological impact of climate changes.

Entropy

Entropy is a captivating concept in thermodynamics that helps describe the level of disorder or randomness within a physical system. In simple terms, it tells us how energy is distributed among particles in a system.

The concept of entropy is crucial in understanding many natural processes. For example, it explains why ice melts at a higher temperature even when energy is applied: as heat is added, molecular motion increases, causing more disorder, or higher entropy. In more technical terms, entropy is associated with the second law of thermodynamics. This law states that the total entropy of an isolated system can only stay the same or increase over time. It implies that processes tend to move towards a state of equilibrium or maximum entropy.

Entropy is an essential factor in determining the direction of natural processes, such as heat transfer or chemical reactions. It's a fascinating subject, bridging the microscopic world of particles with the macroscopic experiences of everyday phenomena.

Water Equivalent

The concept of water equivalent is a unique way of comparing the thermal properties of a substance to water. More precisely, it refers to the mass of water that would absorb or release the same amount of heat as the substance for a given temperature change.

Water equivalent is expressed in terms of mass (usually kilograms) and serves as an interesting perspective for understanding thermal behavior. It helps in practical situations where water acts as a handy reference point due to its prevalent use and well-understood thermal properties.

Here's how it works:

• Suppose a substance has the same water-equivalent mass as a certain amount of water. In that case, both the substance and the water will absorb or release heat in the same way for small temperature changes.
• This comparison can be especially useful in calorimetry, where substances' heat capacities are compared to water's heat capacity to determine absolute and specific heat properties.

In essence, understanding water equivalent allows for efficient and practical comparisons within thermal studies, particularly when examining how efficiently different materials manage temperature changes.