Biomechanics Flashcards
Momentum
Mass x velocity
Amount of motion an object posesses
How can momentum be increased?
- Increase speed
- Increase mass
Law of conservation momentum
Momentum is conserved in any interaction with a closed system (a system that does not lose or gain mass, or isn’t affected by external factors)
Impulse
Force x time
A change in momentum, result of a force acting on an object over a period of time
Methods to increase impulse
Apply a greater force
Apply the force over a greater period of time
Elasticity
The degree of compression then expansion of an object to its original shape
Coefficient of Restitution
The bounciness of an object, measures the elasticity of a collision, and the remaining energy after a collision.
- when a COR = 1 it is a perfectly elastic collision
- when a COR = 0 it is a perfectly inelastic collision
Factors that influence the coefficient of restitution
Temperature
Velocity
Equipment
Surfaces
Equation of COR
square - height of rebround/height of drop
3rd Class Levers
Fulcrum, Effort, Load
Speed Increaser
Moment of Inertia
resistance to rotational motion
Angular Momentum
angular velocity x moment of inertia
refers to the quantity of angular motion possesed by a rotating body.
Angular Velocity
rate of change in angular position of a body
Drag
Horizontal
Lift
Vertical
Turbulent Flow
velocity which at any point varies erratically
Laminar Flow
Fluid moves smoothly in individual streams and layers
Boundary Layer
thin layer of air surrounding of attached to an object
Factors that affect Boundary Layer Seperation
Velocity
-low: boundary layer clings to the surface, seperation is pushed well to the back (reducing drag)
-high: seperation is pushed further forward (increasing drag)
Surface Roughness
- rougher surfaces create turbulent layers, reducing drag e.g. Golf Ball
Shape
-Oval: seperation well to the rear (reducing drag)
-Shape: seperation is further forward (increasing drag)
Surface Drag
Friction created between a fluid and the surface of a moving object
Factors affecting:
- Relative velocity
-Relative roughness
- Surface area of the object
- Viscosity of the fluid
Pressure Drag
Resistance created by a pressure differential between the front and back of an object moving through fluid.
Factors affecting:
-Cross sectional area of the object
- Velocity of the object
- Surface roughness
-Shape
Wave Drag
Creation of waves at the point where air and water interact cauisng resistance to motion
Factors Affecting:
- Relative wave velocity
-Technqiue
-Open vs CLosed water
Slipstream
An area of reduced air pressure and forward suction behind a moving object
Ways to increase balance
Lower centre of gravity
Increase width of base of support
Centralise line of gravity
Increase Mass
Increase number of contact points with the ground
Balance
the ability to neutralise forces that distrub equilibrium or the ability to maintain/hold a position
Sports that recquire less balance
Diving, sprinting, taking off
Sports that recquire more balance
Sumo wrestling, weightliting
Segmental Interaction
forces acting between the segments of a body can transfer energy between them or how body segments interact with one another to meet the task’s demands
Power
More segments used, sequentially summated
Accuracy
Less segments used, simultaneously summated
Simultaneous Movement
All body parts move at the same time to produce a force and accuracy.
Sequential Movement
Combination of forces produced by different body parts acting together producing maximum force.
Principles of effective sequential movement
- Move stronger and larger muscles first followed by smaller and faster muscles
- Sequentially accelerate to ensure that optimum momentum is passed from one body part to the next
- Ensure that each body part is stable
- Use as many body parts as possible
- Follow through to avoid deceleration
- All forces are directed towards the target.
Optimal Projection
the angle at which a projectile must travel in order to maximise distance
Ways to maximise distance
Maximise velocity
Maximise height of release
Angle of release
Bernoulli’s principle
Relates to pressure created by a moving fluid over an object, whereby fast moving fluid creates a low pressure area, and slow moving fluid creates a high pressure area.
Magnus Effect
Force that acts perpendicular to the forward path of moving objects
