Forces in and on the Body PDF

 Forces we are aware of on the body the muscular the force that forces that determines if a the force cause the blood particular atom or involved when to circulate and mo...

 Forces we are aware of on the body the muscular the force that forces that determines if a the force cause the blood particular atom or involved when to circulate and molecule will stay the lungs to at a given place in we bump into take in air the body. objects  The Force Forces in the body Forces on the body Gravitational Nuclear Frictional Dynamic force force force force Electrical Static force force The force of gravity is the force with which the earth, moon, or other massively large object attracts another object towards itself. By definition, this is the weight of the object. All objects upon earth experience a force of gravity that is directed "downward" towards the center of the earth. One of the important medical effects of gravity is the formation of varicose veins in the legs as the venous blood travels against the force of gravity on its way to the heart. Yet gravitational force on the skeleton also contributes in some way to healthy bones. When a person becomes “weightless,” such as in an orbiting satellite, he or she loses some bone mineral. This may be a serious problem on very long space journeys. Long-term bed rest is similar in that it removes much of the force of body weight from the bones which can lead to serious bone loss.  3- Nuclear force A- The strong nuclear force is a very strong, attractive short- range (10-15 m) force that binds the protons and neutrons in the nuclei of atoms together. It is the strongest of the fundamental forces, but acts over a very short distance (10-15 m). B- The weak nuclear force is an extremely short-range (10-18 m) force that acts on the quarks that make up protons and neutrons. It is much weaker than the electric and the strong forces (but still much stronger than gravity at short distances), acts over an extremely tiny distance, and is the cause for beta decay in atoms  1-Frictional force Friction and the energy loss resulting from friction appear everywhere in our everyday life. Friction limits the efficiency we make use of friction when On the of machines such as our hands grip a rope, when other electrical generators and hand we walk or run, and in devices automobiles. such as automobile brakes Friction must be overcome when joints move, but for normal joints it is very small. The coefficient of friction in bone joints is usually much lower than in engineering-type materials. If a disease of the joint exists, the friction may become significant. Synovial fluid in the joint is involved in lubrication, but controversy still exists as to its exact behavior. Some diseases of the body, such as arthritis, increase the friction in bone joints  Friction plays an important role when a A force is transmitted from the person is walking. foot to the ground as the heel touches the ground. The vertical reaction force, supplied by the surface, is labeled N The horizontal reaction component, FH, must be supplied by frictional forces This force can Ff =  N be resolved into vertical and horizontal maximum coefficient components of friction force of Normal between the force friction two surfaces 2- Static force First-Class Lever: the fulcrum is located between the applied force and the resistance. When the force is applied, it can either amplify the force or provide a mechanical advantage for precise control. A common example in the medical field is the use of forceps during childbirth. In this scenario, the pivot point (fulcrum) is the area where the forceps grip the baby's head, the effort (force) is applied by the obstetrician, and the resistance is the baby's head. The leverage allows for the controlled and gentle manipulation of the baby's position during delivery. The The The Applied Fulcrum Resistance Force Second-Class Lever: the resistance is located between the fulcrum and the applied force. These levers provide a mechanical advantage, allowing a smaller force to lift a larger resistance,a wheelchair represents a second-class lever. The pivot point (fulcrum) is the wheel's axle, the resistance is the patient's weight, and the force is applied by the healthcare provider pushing the wheelchair. This lever system makes it easier for a caregiver to move a patient with less effort The The The Applied Resistance Fulcrum Force Third-Class Lever: the applied force is located between the fulcrum and the resistance. These levers do not provide a mechanical advantage in terms of force multiplication but are useful for increasing the range of motion and speed. A common medical example is the use of forceps in dental procedures. In this case, the pivot point (fulcrum) is where the dentist holds the forceps, the applied force comes from the dentist squeezing the forceps handles, and the resistance is the tooth. The lever system provides a precise and controlled way to extract teeth or perform other dental procedures with a wide range of motion. The The The Applied Fulcrum Resistance Force Levers, with their various types, are essential tools in The elbow is a perfect example of one of the medicine, allowing healthcare professionals to perform parts of the body that works as lever, the two tasks with precision and efficiency. Understanding the most important muscles producing elbow principles of levers helps in the design of medical devices movement are the biceps and the triceps. and tools, improving patient care and minimizing physical strain on healthcare providers. The contraction of the triceps causes an extension, or opening, of the elbow, while contraction of the biceps closes the elbow the force exerted by the muscle is much greater than the weight it holds up. This is the case with all the skeletal muscles in the body. They all apply forces by means of levers that have a mechanical advantage less than one, this arrangement provides for greater speed of the limbs. A small change in the length of the muscle produces a relatively larger displacement of the limb extremities.  3- Dynamic force ❖ the human body (and bodies of all animals) is a dynamic system continually responding to stimuli generated internally and by the external environment. Because the center of gravity while standing erect is about half the height above the soles of the feet, even a slight displacement tends to topple the body the simple act of standing upright requires the body to be in a continual back and forth, left right, swaying motion to maintain the center of gravity over the base of support. ❖ In a typical experiment designed to study this aspect of posture, the person is instructed to stand, feet together, as still as possible, on a platform that registers the forces applied by the soles of the feet (center of pressure). To compensate for the shifting center of gravity this center of pressure is continually shifting by several centimeters over the area of the soles of the feet on a time scale of about half a second. Small back-and-forth perturbations of the center of mass (displacements less than about 1.5 cm) are compensated by ankle movements. Hip movements are required to compensate for larger displacements as well as for left right perturbations. The dynamic force is important when the body is moving and hitting another body. It appears on the body where acceleration or deceleration is involved. The Newton's second law, force equals mass times acceleration.