A spring is piece of wire or metal that can be extended or compressed by an external force but which then returns to its original length when that force is no longer applied.

There are many different types of spring including, spiral coil, leaf springs and torsion springs. Springs are used in many applications including clocks, vehicle suspensions etc. In the type of questions that you will be asked in mechanical aptitude tests, you can assume that springs behave in a linear way. That is, doubling the force applied will stretch or compress the spring twice as much.

Springs in Series & Parallel
If more than one spring is used then they can be arranged in one of two ways, either in series or in parallel.

When springs are arranged in series, each spring is subjected to the force applied. When the springs are arranged in parallel the force is divided equally between the springs.

Example Spring Question
1. A force of 5 Kg compresses the springs in series 10cm.What will be the total distance that the springs in parallel are compressed?

·         10cms

·         2.5cms

·         5cms

·         D)7.5 cms

Answer to Question
1. C – The total force will be divided equally between the 2 springs in parallel. Since the force is divided in half, the distance moved will also be halved. The springs in series were compressed 10 cms, so the springs in parallel will be compressed 5 cms.