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The Force Constant k

If a spring obeys Hooke's law, the force applied is directly proportional to the extension.

F ∝ x or F = kxF=forcex=extensionk is the constant of proportionality.The constant of proportionality k is called the force constant and is measured in Nm-1 and is the gradient of a force-extension graph. It is the force per unit extension needed to stretch an object so is a measure of the stiffness of an object.Hooke's law also applies to objects under compression.

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Specification: OCR Physics A (H156), AS-level, 3.4.1 Springs. Topic: Materials.

Key terms in this lesson

tension
The force within a stretched object, such as a rope or cable, that opposes the stretching.
thrust
The force within a compressed object that opposes the compression.
normal contact force
The force that acts perpendicular to the plane of contact between two surfaces, preventing one surface passing through the other.

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