Biomechanics Flashcards
Law of inertia
Body will continue in a state of uniform velocity unless acted upon by an external or unbalanced force
Push or pull that alters the motion
Law of acceleration
A bodys rate of change in momentum is proportional to the size of the force applied and acts in the same direction as the force is applied
The more force, the further it will go
Law of reaction
For every force applied, there’s an equal opposite reaction force
Velocity and equation
Rate of change in displacement
Velocity = displacement/time taken
Momentum and equation
Quantity of motion possessed by a moving body
Momentum = mass X velocity
Acceleration and equation
Rate of change in velocity
Acceleration = (final - initial velocity) / time taken
Force and equation
A push of pull that alters the state of motion of a body
Force = mass X acceleration
What are internal/external forces
Internal
- Generated by skeletal muscle
External
- Outside the body and acts upon in
- Gravity, friction, air resistance
Five effects of forces
Can create motion Can accelerate a body Can decelerate a body Can change the direction of a body Can change the shape of a body
What is net force
The overall motion of the body when all external forces are taken into account
Vertical forces
Weight, arrow down from centre of mass
Weight (N)= mass (kg) X acceleration (m/s/s)
Reaction, arrow up from ground
Horizontal forces
Friction, affected by roughness/temperature of surface and size of normal reaction
Air resistance, affected by velocity, shape, front cross sectional area and smoothness
What is included on free body diagrams
Weight (down)
Reaction (up)
Air resistance (opposite direction)
Friction (same direction)
Horizontal acceleration
Friction > air resistance
Vertical acceleration
Reaction > weight
Balanced forces
Weight = reaction
Constant velocity
What are limb kinematics
Movement in relation to time and space
3D motion analysis using computer software
Data produced immediately and is highly accurate
Helps coaches to select areas for improvement
Specialised, expensive, lab conditions
Force plates
Ground reaction forces
Lab conditions
Jumping, balancing, running on force plates
Gait analysis, balance and rehabilitation
Immediate, accurate, reliable results
Specialised, expensive, lab conditions
Wind tunnels
F1 teams
Aerodynamics of cars
Reducing drag
Specialised, expensive, complex analysis
What is the centre of mass
Point that a body is balanced in all directions
Can be outside the body as a point of rotation
Around naval in anatomical position
Womens slightly lower than mens
What is stability and factors affecting it
Ability of a body to resist motion and remain at rest
- Mass of body increase, stability increase
- Lower COM, stability increase
- Larger base of support, stability increase
- Line of gravity in line with base, stability increase
Features of leaver systems
Lever (bone)
Fulcrum (joint)
Effort (muscular force)
Load (weight/resistance)
Lever classifications
123=FLE
Each feature in the middle
Most are 3rd class
Efficiency of lever systems
Distance from fulcrum is the effort arm
Distance from load to fulcrum is the load arm
Longer levers generate greater forces
Greater the distance of effort from fulcrum, the more significant the load becomes
Mechanical advantages/disadvantages
Seconds class have advantage Effort always longer than load Large load with small effort Efficiency over a small range of motion
Third class have disadvantage
Load longer than effort
Large effort to move a small load
Move load at high velocity and generate acceleration
Transverse axis of rotation
Sagittal plane of movement
Spin front or back
Through one side of the body to the other
Longitudinal axis of rotation
Transverse plane
Round on the spot, 360degrees
Straight down body from head to toe
Frontal axis of rotation
Frontal plane
Through the tummy
