Shadow Power 24

When a body tends to remain in motion because of velocity then it is called inertia of motion. So, the characteristic of a body in motion wanting to keep its motion is called the inertia of motion. The inertia of the motion of a body depends on its momentum. When a moving bus is suddenly stopped, people bend forwards due to the inertia of motion. 

 According to Newton's law, a stationary object will remain stationary and an object in uniform motion will continue its uniform motion. From Newton's first law, a force should be applied to change the stationary and motion state of a body. The characteristics of a body to keep its safe is called inertia.

 Pascal's law is a principle in fluid mechanics given by Balise Pascal that states that a pressure change at any point in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere. 

 Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. 

Economics, or political economy, may be defined, briefly, as the study of men earning a living; or, more fully, as the study of the material world and of the activities and mutual relations of men, so far as all these are the objective conditions to gratifying desires. To define, means to mark off the limits of a subject, to tell what questions are or are not included within it. The ideas of most persons on this subject are vague, yet it would be very desirable if the student could approach this study with an exact understanding of the nature of the questions with which it deals. Until a subject has been studied, however, a definition in mere words cannot greatly aid in marking it off clearly in our thought. The essential thing for the student is to see clearly the central purpose of the study, not to decide at once all of the puzzling cases.

Friction is considered a necessary evil. We cannot do anything without the force of friction. If there was no friction, the motion of a body would not cease at all and continue perpetually. Friction has made it possible to write on paper with a pencil or a pen. We can walk as there is friction between our shoes and the ground. To make life and works easier we need friction. 

At higher altitudes, like hills, cooking food is difficult. Higher altitudes mean lower atmospheric pressure. The boiling point decreases if the pressure is low. So, at the top of the hill cooking takes a long time because due to lower pressure water starts to boil at comparatively lower temperatures. As the temperature cannot be increased, so it takes a longer time to cook. 

Optical fibers are not only used for light communication but it is used in medicine for lighting difficult place of the human body, as for example, internal organ of a man. As a result of application of optical fiber gives clear image of disturbing point. For example doctor gets possibility to check up wall of the stomach by placing wave-guide into stomach. Light is sent through the one of the part of optical fiber for brightness of the stomach and through the other part reflection of light is got at another part of fiber. The instrument based on optical fiber is used for this purpose is called Endoscopes. It is very useful for checking up difficult place of human body, when it needs for operation or fined wound place of patients without any surgical disturbance.

At the interface of two media, the incident light beam is separated into two: reflected and refracted. If light falls with the angle on the surface of the interface, which differs from straight then at the interface light changes its direction. It is called refraction of light. Of the two media in which light propagated at different velocity that in which the light velocity is lower and refraction index, denoted by n is grater will be called optically denser media. For examples glass (n = 1.5 to 1.7) is optically denser then water (n = 1.33). When light propagates from a denser media to light media, then the angle of incidence α1 approaches a certain value α crit, the angle of refraction tends to the right angle α 0  →π/2, and the intensity of the refraction beam tends to zero at a very fast rate. At all angles of incidence excreting αcr which is called the critical angle and there will be no refracted beam. In this case light will be totally reflected from the interface as if it were

In the Figure Illustrates the terms that we use in the study of reflected light. Represents the surface of a plane. AO, called the incident ray, is the direction in which light falls onto the reflecting surface. O is the point of incidence and OR the, reflected ray. The angles, which the incident and reflected rays make with ON, the normal or perpendicular to the reflected surface at the point of incidence, are, called the angles of incidence and reflection respectively. Laws of reflection are - ♦ The incidence ray, the reflected ray and the normal at the point of incidence all lie in the same plane. ♦ The angle of incidence is equal to the angle of reflection.