Moderate -0.5 This is a straightforward application of Hooke's Law (F = λx/l) with direct substitution of given values to find compression, then a simple subtraction to find the distance between plates. It requires only one formula and two arithmetic steps, making it easier than average but not trivial since students must correctly identify the setup and apply the elastic string/spring formula.
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\includegraphics[max width=\textwidth, alt={}, center]{68acf474-5da2-4949-b3b2-fc42cd73bd4a-2_113_787_264_680}
A light elastic spring of natural length 0.25 m and modulus of elasticity 100 N is held horizontally between two parallel plates. The axis of the spring is at right angles to each of the plates. The horizontal force exerted on the spring by each of the plates is 20 N (see diagram). Find the amount by which the spring is compressed and hence write down the distance between the plates.
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\includegraphics[max width=\textwidth, alt={}, center]{68acf474-5da2-4949-b3b2-fc42cd73bd4a-2_113_787_264_680}
A light elastic spring of natural length 0.25 m and modulus of elasticity 100 N is held horizontally between two parallel plates. The axis of the spring is at right angles to each of the plates. The horizontal force exerted on the spring by each of the plates is 20 N (see diagram). Find the amount by which the spring is compressed and hence write down the distance between the plates.
\hfill \mbox{\textit{CAIE M2 2009 Q1 [3]}}