Biomechanics Flashcards
Linear motion
The motion of an object in a line, either curved or straight. eg. a ball following a parabolic pathway, an ice skater gliding straight
Angular motion
When an object turns around an axis of rotation. eg. ice skater spinning, diver performing a somersault
General motion
Combination of linear motion and angular motion. eg. a cyclist moving in a straight line as a result of the rotation of the legs around the hip joint
Acceleration definition and formula
Rate at which the velocity of a body changes with respect to time.
Acceleration = final velocity - initial velocity/time
Speed formula
Speed = distance/time
Velocity definition + formula
Speed in a given direction.
Velocity = Displacment/Time
Force
any push or pull acting on a body
Newton’s first law
A body will remain at rest or continue in its state of motion unless acted upon by an external force
Newton’s second law
The rate of change of acceleration of a body is proportional to force applied to it. (F=ma)
Momentum
Momentum is the quantity of motion of a moving body. Formula: Momentum = mass x velocity
Conversion of linear momentum
This principle states that the total momentum of two objects before and after a collision are equal.
Impulse
An impulse refers to the change in momentum experienced by an object or body part when a force is applied to it over a specific period of time. Impulse = force x length of time force applied
How to absorb momentum
Absorb the force over a long time period. This reduces the peak force.
Newton’s third law
For every action, there is an equal and opposite reaction
Balance
Balance is the state of equilibrium between two or more opposing forces, factors or elements.
Importance of base of support in balance
Base of support is defined as the area beneath a person that includes every point of contact that person makes with the supporting surface. In order to maintain balance, the base of support should be wide and stable. A wider base of support provides more stability and reduces the likelihood of tipping over.
In sumo wrestling, wrestlers often adopt a wider stance with their legs apart to increase their base of support and improve their stability
importance of line of centre of gravity in balance.
The line of center of gravity represents a vertical line passing through the center of gravity of an object. When an object is balanced, the line of center of gravity should pass through the base of support. If the line of center of gravity falls outside the base of support, it causes instability.
In skiing and snowboarding, maintaining a proper line of center of gravity is crucial for balance. Leaning too far forward or backward can cause loss of balance and potentially lead to a fall.
Importance of height of centre of gravity in balance.
The centre of gravity is the point around which a body’s weight is equally balanced in all directions. The height of the center of gravity plays a crucial role in balance. For stable balance, the center of gravity should be positioned within the base of support. If the center of gravity is too high and outside the base of support, it can cause instability and make an object more prone to tipping over.
In high jump, athletes arch their bodies backward as they pass over the bar. By lowering their center of gravity during the jump, they enhance stability and reduce the chances of knocking down the bar.
How does the principle of balance apply to mass? Give a sporting example.
The distribution of mass within an object affects its balance. Objects with uneven distribution of mass are less likely to maintain balance compared to those with a more even distribution of mass.
In basketball, players with a larger mass have an advantage in maintaining balance when driving to the basket, as they can withstand contact from defenders without losing stability.
How does the principle of balance apply to static balance? Give a sporting example.
Static balance refers to the ability of an object to remain stable and stationary without any external forces acting upon it. Achieving static balance requires the object’s center of gravity to be positioned directly above its base of support
In yoga and when holding a stretch, static balance is essential for holding poses or executing techniques.
How does the principle of balance apply to dynamic balance? Give a sporting example.
Dynamic balance refers to the ability of an object or a person to maintain balance while in motion or during dynamic activities. In dynamic balance, the object’s or person’s center of gravity shifts and adjusts as movements occur to maintain stability and prevent falling over.
In surfing, maintaining dynamic balance is crucial to stay upright and navigate the changing forces of the waves. Surfers continuously adjust their body position and weight distribution to stay balanced on the board
First class lever
fulcrum in the middle. eg. seesaw
Second class lever
load in the middle. eg. wheelbarrow
Third class lever
force in the middle. eg. golf, tennis
3 factors affecting lever use
Length of lever, inertia of lever, amount of force
