In modern mechanics, Sir Isaac Newton comes in handy through his various laws that help explain the effect of force on bodies. These laws include the law of inertia which explains why a body will remain intact or in constant velocity if there is no force applied to it. The law of Acceleration entails why a body will accelerate in proportionality to the force applied and towards the direction of the force. The third law is the Law of Reaction, which seeks to explain why there is an equal force on the body exerting pressure and the other that pressure is being exerted on thus an equal and opposite force. Lastly, The Law of Gravitation explains the attraction between bodies, for instance, the apple and earth. Bodies with high mass have a higher attraction force between them and when the distance between them is added, there will be decrease in attractive force.
Friction is a resisting force observed between the surfaces of bodies that are in contact but moving in the opposite direction. The amount of force could be affected by factors that include the roughness of the two surfaces and the interaction between the molecules of the two bodies. The more the surfaces are rough, the higher the coefficient of friction. Friction could be increased or decreased intentionally for effectiveness in different situations. For instance, use of gloves in football and racquets helps increase the coefficient of friction, thus enabling players have ease handling the ball. Friction is also essential when walking because when the coefficient of friction is high, a person is more comfortable and can walk with ease, unlike when the friction is low, which will cause slipping. Friction and air resistance exist and act to slow skaters and other moving bodies.
Momentum refers to a body’s amount of motion. A body with no velocity has no momentum. It could be affected by a change in velocity or mass of a body. The interrelation of this can be seen where a body of less mass is moving at a higher speed collides with one moving at a slower speed but with a higher mass will tend to still move in the initial direction which leads us to our next topic on impulse. Impulse is an outcome of force and time on a body, impulse=Ft. Humans control impulse in different situations that include jumping, catching a ball.
Impact refers to a collision between two bodies over a short period of time. Impact could be affected by the nature of collision where there will be higher impact when the surfaces are hard and low impact when surfaces are soft. This explains why a tennis ball will bounce higher on a concrete court than on a gras court because the hardness of the surfaces is different. The coefficient of restitution is the relative elasticity of an impact which number between 0 .and 1. When the value is closer to one, the elasticity is said to be higher and thus lower impact. plains a
Work is the amount of energy on a body by an external force. Muscles could have produced negative or positive work when they produce tension to enhance movement of a body segment. In a case of working out, a person could be aiming at building a certain muscle. This is where they should pay attention to what type of exercise they are undertaking so as to realize a positive impact on the body. The law of conservation of mechanical energy illustrates why the mechanical energy of a body will remain the same when gravity is the only force acting on it.
The principle of work and energy seeks to explain the unique relationship between the quantities of mechanical work and mechanical energy. The work done by a force is dependent on the sum of forms of energy produced by it. During projection of a tennis ball into the air by a machine, the mechanical work on the ball increases the mechanical energy of the ball. This relationship could also be illustrated with the human body, where the arches in the feet act to store energy by acting as springs, thus reducing mechanical work which could be used in the running.