GCSE Physics Tutorial - Recall that Work is the Transfer of Energy by a Force on a Gas
In this tutorial, we will recall the concept that work is the transfer of energy by a force on a gas. Understanding this fundamental principle is essential in comprehending how work can be done on a gas, leading to changes in its internal energy. Work done on a gas can affect its temperature, pressure, and volume, and it plays a significant role in various real-world applications. Let's explore the world of work on gases and its implications!
Work and Energy Transfer: Work is a physical quantity that measures the transfer of energy from one system to another due to the application of a force. When work is done on a gas, energy is transferred to the gas, leading to changes in its internal energy.
Work on a Gas: Work done on a gas can result in two scenarios:
a. Gas Expansion: When work is done on a gas causing it to expand, energy is transferred to the gas, increasing its internal energy. This leads to an increase in the gas's temperature and volume.
b. Gas Compression: When work is done on a gas causing it to compress, energy is transferred from the gas to the surroundings. This decreases the gas's internal energy, resulting in a decrease in temperature and volume.
Work Formula for a Gas: The work done on a gas can be calculated using the pressure-volume equation:
Work (W) = Pressure (P) × Change in Volume (ΔV)
Where: W = Work done on the gas (measured in joules, J) P = Pressure applied to the gas (measured in pascals, Pa) ΔV = Change in volume of the gas (measured in cubic meters, m³)
Positive and Negative Work on a Gas:
If the gas expands (increases in volume) and the pressure is applied to push the gas, work is done on the gas, and the work is positive.
If the gas is compressed (decreases in volume) and the pressure is applied by the gas to resist compression, the work is done by the gas, and the work is negative.
Applications of Work on Gases: The concept of work on gases has practical applications in various fields:
Thermodynamics: Work done on or by gases is crucial in understanding thermodynamic processes and the efficiency of heat engines.
Compressed Gas Systems: In industrial applications, work on gases is used in compressed air systems and gas turbines.
Climate and Weather: Work on gases plays a role in understanding atmospheric processes that influence weather patterns.
Sample Questions:
Question 1: A gas inside a cylinder expands from a volume of 0.02 m³ to 0.06 m³ while the pressure on the gas remains constant at 3000 Pa. Calculate the work done on the gas during this expansion.
Solution: Using the work formula for a gas: Work (W) = Pressure (P) × Change in Volume (ΔV) ΔV = 0.06 m³ - 0.02 m³ = 0.04 m³
W = 3000 Pa × 0.04 m³ W = 120 J
Answer: The work done on the gas during this expansion is 120 joules.
Question 2: A gas inside a piston is compressed from a volume of 0.05 m³ to 0.02 m³. The pressure on the gas increases to 5000 Pa during compression. Calculate the work done by the gas during this compression.
Solution: Using the work formula for a gas: Work (W) = Pressure (P) × Change in Volume (ΔV) ΔV = 0.02 m³ - 0.05 m³ = -0.03 m³
W = 5000 Pa × (-0.03 m³) W = -150 J
Answer: The work done by the gas during this compression is -150 joules.
In this tutorial, we have recalled the concept that work is the transfer of energy by a force on a gas. Understanding work on gases is crucial in various real-world applications, such as in thermodynamics, industrial processes, and climate studies. Work done on a gas can lead to changes in its internal energy, affecting its temperature, pressure, and volume. Keep exploring the fascinating world of physics to uncover more exciting concepts and their applications in practical situations.
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