The stiffness of a spiral spring depends on its physical dimensions and the rigidity of the steel strip from which it is formed. With the Torsion of Spiral Spring Apparatus student can easily calculate the theoretical stiffness of the spring, and compare the value with simple experimental results. Spiral springs are used to provide a resisting or restoring torque to a shaft when it is rotated through an angular displacement. One end of the spring is attached to a shaft mounted in ball bearings. A load hanger and calibrated weights is used to incrementally load the spring. They exhibit similar stiffness characteristics to linear springs, except that the effect is one of torque rather than force. The wall mounted unit consists of a spiral spring coiled from a length of steel strip. Spring deflection is measured with an attached scale.
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