GCSE Physics Tutorial - Compression and Extension
In physics, when we talk about materials experiencing a force and changing their shape, we often refer to either extension or compression. Extension is when a material is stretched or elongated due to an applied force, while compression is when it is squeezed or shortened. Both extension and compression are types of deformation, and they follow similar rules based on Hooke's Law.
Hooke's Law and Elastic Behaviour: Hooke's Law states that the force applied to a material is directly proportional to the extension or compression it undergoes, as long as the material behaves elastically. This means that within the elastic limit, the material will return to its original shape and size once the applied force is removed. Hooke's Law can be represented as F = k * x, where F is the force, k is the spring constant, and x is the extension or compression.
Extension and Compression: Same Rules, Different Directions: The crucial point to understand is that the rules governing extension also apply to compression, with one key difference - the direction of the deformation. Let's see how both processes follow the same rules:
Force-Extension Relationship: When an external force is applied to stretch a material (extension), it experiences a displacement or increase in length. The extension, x, is measured in the direction of the force. According to Hooke's Law, the extension is directly proportional to the applied force. If you double the force, the extension will also double, as long as the material behaves elastically.
Force-Compression Relationship: When an external force is applied to compress a material, it experiences a displacement or decrease in length. The compression, x, is measured in the direction opposite to the applied force. Like in extension, the compression is also directly proportional to the applied force. If you double the force, the compression will also double, as long as the material behaves elastically.
Elastic Limit: Both extension and compression are subject to the elastic limit of the material. If the applied force exceeds the elastic limit, the material will undergo plastic deformation, and it will not return to its original shape once the force is removed.
In summary, compression follows the same rules as extension based on Hooke's Law. Both extension and compression are types of deformation experienced by materials when subjected to external forces. The force-extension relationship applies to both cases, and the extension or compression is directly proportional to the applied force, as long as the material behaves elastically. Understanding these principles is essential for comprehending the behaviour of materials under various forces and for practical applications in engineering and other fields.
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