Physics around Us


The word physics is taken by scientist as synonymous to nature. It involves the study of matter as well as its motion and behavior in space and time. It is related to energy and force. In science, a principle is defined as a fundamental law or truth from which others laws are derived. In science, such principles govern nature and can be used to explain occurrences/ observations in our day to day life. Such occurrences/observations range from household, environmental, agriculture, infrastructure, transport, and energy among others. They also explain how various equipment and machinery work and the reason for their design.

One of my observations is the breaking system of an automobile. In this case, we assume that the car is in good condition. (Owen) When the driver steps on the brakes pedal/lever, the car stops without some wheels stopping before the others. This is proved so by the fact that it does not turn or skid when stopped. From this we can deduct that when driver steps on the brakes pedal, it is like he steps on four pedals each one representing each one of the four wheels at the same time. The four wheels stops at the same time.

The system uses an incompressible fluid for the transmission of force from the pedal to the wheels. Basically the system comprises of a pedal, the return springs, the master cylinder, fluid pipes, slave cylinders, brake shoes and drum.

Modern systems have added components like boosters and brake pads replacing the shoe. They improve the efficiency, reliability and durability of the system but all in all both modern and simple systems apply the same ideal breaking system or one that is not malfunctioning should have an incompressible fluid. It is mostly a liquid that does not have air bubbles or in other words what is referred to as cavitation. The fluid should also occupy the whole space in the connecting pipes. This arrangement of fluid filled pipes is referred to as hydraulics. The fluid is referred to as hydraulic fluid. Apart from transmitting force, the hydraulic fluid also multiplies the force since the force required to stop a car or else a truck is much greater than the force applied on the pedal.

When one presses the brakes pedal, the force is transmitted to the master cylinder. It is then transmitted to the four slave cylinders at each of the four wheels(Owen).The force forces the piston of the slave cylinder to push the brake shoes to the drum. The friction between the shoe and the drum forces the drum to stop rotating thereby stopping the wheel and so is the car. Friction is the resistance that one surface or object encounters when moving over another.

Multiplication of force and equal distribution is achieved using the principle of transmission of fluid pressure. It was first enunciated by a French scientist, Braise Pascal. It postulates that a “pressure change occurring anywhere in a confined incompressible fluid is transmitted throughout the fluid such that the same changes occur everywhere”.(Durfee etal). According to Pascal, pressure at a point in a fluid at rest is the same in all directions. Pressure is force per unit area. It is measured in bars or in Newton per square meters. From the definition it is evident that when a change in force and area occurs, pressure will remain constant. Thus,

P=F/A where P=Pressure, F=Force, A=Area.

Considering that pressure is constant, force is directly proportional to cross section area(Durfee etal) The smaller the area, the higher the force. In the case of a car, the diameter of the tube from the pedal to the master cylinder is almost the same size as the diameter of the tube from the master cylinder to the wheels. This is so since the system also used the distance moved by the force to compensate for the drastic difference between the two forces.

Work input = work output

Work done = force x distance

Therefore: F1D1 = F2D2

This means that the distance moved by the force on the pedal is higher than the distance moved by force from the shoe original point to the drum. On the other hand, the force on the pedal is much less than the force on the drum.

Pascal’s principle is also used in other hydraulic machines and equipment. For example a car jack, hydraulic press, hydraulic lifts etc.

In hydraulic press, the piston area is smaller than the ram area. Consequently, the piston is observed to moves at a longer distance than the pressing plate.(Durfeeet al) The force on the piston is much less than the force on the load. A price has to be paid by exerting a smaller input force through a larger distance. The force in the smaller cylinder is through a long distance is traded to a larger force exerted on the large cylinder through a small distance.


Science plays a big role in explanation of what we see and why matter behaves the way it does. Through research, scientists have solved many problems that would otherwise be affecting us on daily basis.

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