18 Questions
What is the outcome of natural processes in terms of entropy?
Entropy maintains or increases in the universe
What happens to the energy when gasoline is burned in a car engine?
It is degraded into less useful forms
What is the effect of adding heat to a system on its entropy?
Entropy increases
What is the relationship between internal energy and entropy?
Internal energy and entropy are both contained in an object
What is the equation that represents the change in entropy of a system?
ΔS = q / T
What is the main purpose of thermodynamic applications in engines?
To transform high-quality energy into less useful energy
What is the unit of entropy?
Joules per kelvin
What is the temperature at which the entropy of a perfect crystal is zero?
Absolute zero
What is the minimum temperature that can be achieved by a system?
Absolute zero
What is the internal energy of a system changed by?
The difference between the heat absorbed and the work done
What is an example of a real-world application of thermodynamics?
An automobile engine
What is the significance of absolute zero in thermodynamics?
It is the temperature at which all molecular motion stops
What is the lowest temperature that can be achieved by a system according to the laws of thermodynamics?
Absolute zero
What is the measure of the disorder in a system?
Entropy
Which law of thermodynamics states that the internal energy of a system is equal to the heat added to the system minus the work done by the system?
First law of thermodynamics
What is the energy in transit referred to as?
Heat
When is work done by the system?
When the system is expanding
What is the concept of thermal equilibrium defined by?
Zeroth law of thermodynamics
Study Notes
Second Law of Thermodynamics
- The second law of thermodynamics states that natural processes go in a direction that maintains or increases the total entropy of the universe.
- It means that all usable, high-quality energy is turned into less useful energy.
- Example: when gasoline is burned in a car engine, it degrades into non-useful forms of energy and cannot be used to fuel another engine again.
Entropy
- Entropy is a measure of the disorder in a system.
- It is contained in an object and can increase or decrease depending on the heat added or removed.
- If heat is added to the system, its entropy increases, and if heat is removed, its entropy decreases.
- The change in entropy of a system is equal to the heat added to the object divided by the temperature of the system in kelvins (ΔS = q / T).
Third Law of Thermodynamics
- The third law of thermodynamics states that the entropy of a perfect crystal is zero when the temperature of the crystal is equal to absolute zero (0 K).
- It implies that it is not possible to lower the temperature of any system to absolute zero in a finite number of steps.
- Absolute zero (0 K) is equivalent to -273.15°C, a temperature where there is no thermal motion anymore.
Thermodynamics Applications
- Thermodynamics has practical applications in automobile engines, refrigerators, air conditioning, food preservation and packaging, and large-scale power generation.
Important Concepts
- Internal energy is the total energy within a substance.
- Heat is the energy in transit.
- Work is done by the system when it is released, and heat is released by the system when it is transferred.
Learn about the second law of thermodynamics, entropy, and energy transformation in this quiz on heat and thermodynamics from Grade 9 Science Unit 17.
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