Concept about Gravity – Introduction to fundamental concepts of Biological Science including the organization and common characteristics of living matters, cell structures and functions, food production by photosynthesis, harvesting energy, mechanism of cells reproduction, genetics, evolutions, and Human Biology. Introduction to general chemistry including basic concepts about matter, atomic structure, chemical bonds, gases, liquid, and solids, solutions, chemical reactions, acid, bases, and salt;
organic and biochemistry including hydrocarbons and their derivatives, carbohydrates, lipids, proteins, enzymes, vitamins, and minerals, nucleic acids; principles of physics and applications to nursing including gravity and mechanics, pressure, heat and electricity; nuclear chemistry and nuclear physics, effects of radiation on human beings, and protection and disposal. The aim of the course is to acquire knowledge and skills in general biological science, general chemistry and physics.
Concept about Gravity
Gravity is a force of attraction that exists between any two masses, any two bodies, and any two particles. Gravity is not just the attraction between objects and the Earth. It is an attraction that exists between all objects, everywhere in the universe. Sir Isaac Newton (1642-1727) discovered that a force is required to change the speed or direction of movement of an object. He also realized that the force called “gravity” must make an apple fall from a tree, or humans and animals live on the surface of our spinning planet without being flung off. Furthermore, he deduced that gravity forces exist between all objects,
Newton’s “law” of gravity is a mathematical description of the way bodies are observed to attract one another, based on many scientific experiments and observations. The gravitational equation says that the force of gravity is proportional to the product of the two masses (m₁ and m₂), and
inversely proportional to the square of the distance (r) between their centers of mass Mathematically speaking,
- F-Gm1m2/r²,
Where G is called the Gravitational Constant. It has a value of 6.6726 x 10-11 m³ kg s².
The effect of gravity extends from each object out into space in all directions, and for an infinite distance. However, the strength of the gravitational force reduces quickly with distance. Humans are never aware of the Sun’s gravity pulling them, because the pull is so small at the distance between the Earth and Sun. Yet, it is the Sun’s gravity that keeps the Earth in its orbit! Neither are we aware of the pull of lunar gravity on our bodies, but the Moon’s gravity is responsible for the ocean tides on Earth.
Definition of Gravity
Gravity is the force that attracts two bodies toward each other, the force that causes apples to fall toward the ground and the planets to orbit the sun. The more massive an object is, the stronger it’s gravitational pull.
or
Gravity or gravitation, is a natural phenomenon by which all things with mass or energy including planets, stars, galaxies, and even light-are brought toward (or gravitate toward) one another
Clinical Application of gravity:
1. The circulation of the blood in the body depends largely on gravity. Changes in body position alter the pressure of the blood in different parts of the body. During fainting spell the brain is temporarily deprived of blood. People who stand on their feet for a long time may have oedema of the legs and feet
2. Without gravity, there will be no pressure in liquids, and therefore, no irrigations, intravenous infusion, or blood transfusions will be possible.
3. Postural drainage is a treatment in which the patient lies on his abdomen across the bed with his chest and head hanging down over the sides of the bed. It is the application of principle of gravity to effect drainage from the lungs.
4. A diagnostic test based on gravity is the erythrocyte sedimentation rate (ESR),
5. Following brain surgery the head of the bed may be elevated to facilitate draining the blood from brain.
6. Gravity exercises are prescribed for patients with circulatory disorders of the lower extremities.
Principles of Centre Gravity:
Centre of gravity is considered to be the point at which all external forces are applied on an object. If an object is suspended from this point, it will remain in balance without turning whatever its position is. In general, the centre of gravity (or centre of mass) of a body is the point at which all the mass is considered to be centered. Principles of centre of gravity as they apply to body mechanics should be known by the nurse before beginning any strenuous activity. Three basic generalizations that should prove helpful are as follows:-
1. The muscles of lower extremities are powerful antigravity muscles, vity muscles, Whenever possible, these muscles rather than the back muscles should be used
2. In lifting objects, decreasing the length of the effort arm decreases the force that the body muscles must apply.
3. Most of the heavy organs are located in the anterior part of the body so it is important to prevent the body from sagging anteriorly.
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