An external force acting on an object is said to be compression force if it tends to reduce the original size of the object. Typically, compression can be observed by squeezing an object with the help of a mechanical force applied on it from the outside. Depending upon the nature of the object, compression force may lead to a temporary or permanent alteration of the object’s structure. This happens due to the displacement of the atoms from their original position to a relatively different position. Different types of objects have their respective responses to the compression force. For instance, brittle objects break upon being compressed, while elastic objects, when subjected to compression force, regain their original shape as soon as the force is removed. The compression force is an inward force as it acts on the inside of the structure.
Examples
1. Bridge
A suspension bridge experiences tension force and compression force when a vehicle approaches the structure. The vehicle passing through the bridge receives a gravitational pull towards the centre of the earth and presses the bridge to the downward side. The columns and beams that are used to support the structure of the bridge experience a compression force due to the gravitational force acting on the vehicle. If the compression force is significantly high in magnitude, it may cause cracks in the structure of the bridge. This is the reason why proper analysis, calculation, and research of compression force is done to know the threshold limit of pressure handling before constructing a bridge.
2. Hydraulic Press
A hydraulic press consists of two cylinders connected to each other. The larger cylinder is known as a ram, while the smaller cylinder is known as a plunger. Both the cylinders contain a hydraulic fluid that acts as a medium to transfer the energy to the machinery. The machinery works upon the principle of Pascal’s law, which states that pressure applied to a small portion of a liquid is shared by the complete volume of the liquid present in the container. When the plunger is pushed down, the hydraulic fluid present in it gets compressed; therefore, according to Pascal’s law, the compression gets transferred to the fluid present in both cylinders. The pressure developed due to the compression of fluid present in the ram lifts it up. The compression force existing in both cylinders is, therefore, used to crush the material present in between them.
3. Spring
When a mechanical or muscular force is applied across both ends of spring, it tends to change its shape. When the force applied is inward in nature, the spring tends to get compact in size. In such a case, a compression force is said to be existing. Similarly, when the force applied is external in nature, the spring gets stretched and a tension force is said to be present.
4. Shoe Sole
When a person walks or runs, the pressure is exerted on the shoe by the foot of the person and the reaction force applied by the ground. This tends to develop a significant amount of compression force on the shoe sole, which deforms the shape of the shoe temporarily. The magnitude of the compression force depends upon the weight of the body, which further depends on the magnitude of gravitational force acting on it.
5. Bicycle Pump
When the piston of the bicycle pump is pulled up, it sucks the air. The air enters the pump through the inlet and gets deposited in the chamber. When the piston is pushed downwards, the inlet gets closed. This compresses and forces the air to leave the chamber through the outlet. Hence, the working of a bicycle pump is highly dependent on the action of compression force.
6. Sponge
A sponge is one of the best examples that demonstrate the existence of compression force in real life. The sponge has an elastic structure, which is why it is able to regain its original shape as soon as the effect of the externally applied force fades away. When a push force is applied across both ends of the sponge, it tends to squeeze and the original size of the sponge gets reduced. Hence, a compression force is said to be present.
7. Plush Toys
Plush toys are made up of soft material. When such toys are squeezed by applying a firm muscular force, they tend to lose their original shape. The force responsible for the deformation of the original shape of a plush toy is known as a compression force.
8. Air Suspension System
A number of buses make use of an air suspension system to improve fuel consumption, suppress engine noise, and extend tire life. An air suspension system makes use of an engine-driven or an electric air pump. This pump is used to compress the air into the rubber bags connected to it, known as bellows. The inflated bags are able to act as springs and provide the necessary suspension to the vehicle for a smooth drive.
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