Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 3 (NEWTON'S LAWS OF ANGULAR MOTION (Conservation of angular…
Chapter 3
-
FORCE
-
The force of gravity will pull a ball back to the ground after it has been thrown, hit or kicked.
-
-
All forces produce or alter movement, but this effect is not always obvious e.g. when jumping off ground, the force back on the earth cannot be noticed
Force can be calculated by multiplying the mass of the object by its acceleration: FORCE = MASS X ACCELERATION
INERTIA
-
Is the tendency for a body to resist a change to its state of motion, whether that state is at rest or moving with a constant velocity
In the human body, muscles provide the force to start or stop motion, accelerate or decelerate, or change direction
-
The amount of inertia an object has is directly related to its mass. The greater the mass of an object, the greater its inertia, and the greater the force needed to change its state of motion
If the force applied to an object, there will be no change in the object's motion. The strength of a muscle is related to the force it can produce
BIOMECHANICS
-
Using the principles of physics associated with motion and forces, biomechanics can help develop and refine human movement. It also enables us to refine movement in order to improve performance
Looks at the structure and design of equipment used sport, movement techniques, the causes of overuse injuries, impaired mobility in the elderly, maintaining bone density in space, and improving movement in people with disabilities such as cerebral palsy and lower-limb amputations.
Elite athletes use biomechanics analysis to improve their performance, equipment and technique, but the correct application of biomechanics principles can lead to improved performance, greater efficiency and accuracy at all levels of sport and physical activity
-
-
TYPES OF FORCE
In sporting situations, these forces can speed up, slow down or change the direction of a ball, bat or body.
-
Friction
Occurs when 2 surfaces come in contact with each other, Friction opposes the motion of an object
In sporting situations, there are times when it is beneficial to decrease the friction between two surfaces, such as downhill skiing. In other examples, it may be important to increase the friction between the surfaces
Manipulating the amount of friction between surfaces is common in physical activity, sport and exercise
-
Sports shoes are designed to utilise friction, help prevent injury
To start an object moving across a surface, you must first overcome friction by applying an increasingly greater force. As the applied force increases, so does the friction, to a certain point
The max amount of friction that can be generated between two non-moving surfaces is called maximum static friction. If the force applied increases beyond the maximum static friction value, then the object will begin to move
-
Weight
-
-
Weight is directly proportional to the mass of an object. It can be calculated by multiplying mass by the acceleration due to gravity. WEIGHT = MASS X GRAVITY
MOMENTUM
-
-
An object that is not moving would have zero momentum because it has no velocity. However, if two objects have the same mass but different velocities, the object with the greater velocity will have the greater momentum
Conservation of momentum
-
The principle states that the total momentum of the system before the collision is equal to total momentum after the collision
In conservation of momentum, we need to look at the objects involved in the collision before and after impact
The total momentum of the two objects before the collision can be found by adding the two individual momentums together. Therefore, the total momentum before the collision is equal only to the momentum.
Summation of momentum
When the main objective of a sport is to hit, kick or throw an object as far as possible, it is important that the object is released or struck with maximum velocity
Any movement skill that involves multiple joint requires summation of momentum from the beginning of the movement to the end.
Maximum velocity results from momentum being generated in a sequential manner, from the body parts closest to the centre of gravity to those furthest away.
By coordinating all of the body segments that are involved in the movement, athletes are able to generate maximum velocity
IMPULSE
-
To change the momentum of an object, a force must be applied over a period of time. Impulse is equal to the force applied multiplied by the length of time the force was applied: IMPULSE = FORCE X TIME
Impulse is an important quantity in sporting situations. Any change in momentum will be the result of a change in velocity, because the mass of the object will remain the same
A change in an objects momentum can result from large force being applied over a very short period of time or a small force being applied over a longer period of time
NEWTON'S LAWS OF MOTION
NEWTON'S FIRST LAW
'A body's will remain at rest or in uniform motion in a straight line unless acted upon by an external force'
E.G. A soccer ball won't move from the position it has been placed in until a player applies a force by kicking it
NEWTON'S SECOND LAW
' A force applied to an object will produce a change in motion (acceleration) in the direction of the applied force that is directly proportional to the size of the force'
Acceleration that occurs is proportional to the force and inversely proportionate to the mass of the object
-
If the mass of an object is known and the applied force is known, the the resulting acceleration can be calculated.
NEWTONS'S THIRD LAW
-
When two objects come into contact with one another, they exert forces that are equal in size but opposite in direction on each other. They don't cancel each other out
E.g. When running, we push down and back with our feet and the surface pushes up and forward
Running on a track is easier than running on sand, because the sand dissipates the force applied by the foot, reducing the reaction force.
QUANTITATIVE
Is based on measurement of kinetic (force) and kinematic (distance, speed, acceleration) variables
-
QUALITATIVE
Involve descriptions, can be general or highly detailed
Coaches, teachers and trainers rely heavily on qualitative observations to provide feedback to students and athletes