A magnet is used to attract or repel another object. It uses its magnetic field to apply these forces to other objects. As The Science Bus Experience explains, the Earth is a big magnet due to the molten metals that are at its centre. A spring also exerts two opposing forces. The coil of a spring can be stretched or compressed. By taking advantage of these forces, magnets and springs have many uses.
A compass would not work without a magnet. Inside the compass is a magnet which moves to line up with the Earth's natural magnetism. The north pole of the magnet is attracted to the south pole of the Earth. As such, the magnet moves to always be lining up in this way. When you use a magnet, you can see this in action as the needle moves around to always point northward and from knowing this, you can tell which way you are facing.
Magentic Resonance Imaging
Magnetic Resonance Imaging, more commonly known as MRI scanning, is an important procedure that uses magnets in hospitals. It is used to produce images of the brain or body tissues which are used in diagnosing the presence of tumours or other abnormalities. A patient lies inside a cylinder that is essentially a giant magnet which sends radio waves through the body. This changes the direction of the body's atoms. Computers can detect these changes and turn them into images for assessment.
Coil springs, leaf springs, shock absorbers and a suspension system are all built into a vehicle. In each case, springs are used to absorb movements of the car to keep it steady while driving. For example, when a car goes over a bump in the road the coil spring compresses and moves upward. This pushes against the suspension arm, causing it to extend. This enables the wheels of the car to be kept in contact with the road when going over bumps.
Trampolines, seesaws and other playground rides use springs within their mechanisms. A trampoline, for example, has an elasticated surface that stretches and compresses as the user bounces up and down on it. The elastic is a type of spring. Playgrounds also contain hobby horses which bob quickly back and forth. This movement is created by the pull and push of a spring under the base of the horse.
Many clocks operate using a spring mechanism. The Encyclopedia Britannica explains how -- during the 1600s -- a Dutch astronomer designed a mechanism inside a clock using springs. He created a spring, or small coil, that stretches and compresses at regular intervals to time the movements of the hands on a clockface. This design modernised the clock mechanism from the early 1500s. During this period, clocks operated using springs. However, in addition to the spring, a magnet (sundial and compass) was used as a backup because the clocks were inaccurate.
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