Lecture 1 Flashcards
Biomechanics
the study of the structure and function of biological systems by means of the methods of mechanics
Uses engineering techniques to study biological systems.
Injury
The damages sustained by tissues of the body in response to physical trauma
Orthopedics
A branch of medicine dealing with correction of deformities of bones or muscles
Mechanics
France of science that deals with the effects of forces and energy on bodies
Mechanism
The fundamental physical process responsible for a given action, reaction, or result
Disease
A disorder of structure or function in a human, animal or plant, especially one that produces specific signs or symptoms or that affects a specific location and is not simply a direct result of physical injury
Examples of Unintentional Injuries:
Car accidents Poisonings Fires and Burns Drug abuse Falls Drowning
Epidemiology
The study of the incidence, distribution, and control of disease and injury in a given population
Types of epidemiology studies
Descriptive - Frequency and distribution
Analytical - Casual Relations
Intrinsic risk factors in Sports Injuries
Age
Flexibility
Previous Injury
Somatotyple
Causation in Sports injury
Intrinsic risk factors predisposes the athlete + Exposrues to extrinsic risk factors makes the athlete susceptible to an injury. Inciting event to a susceptible athlete = Injury
Prevention and control of injuries
Health and safety education
Prevention of hazard creation
Visual reminders
Sports Specific:
Equipment
Rules
Prevention and control of injuries
Health and safety education
Prevention of hazard creation
Visual reminders
Sports Specific:
Equipment
Rules
Kinematics
Measurement of description of movement
Forms of Movement
Linear (ie translation)
Angular (ie rotation)
General (combination of above two)
Linear Motion
All points on the body move in the same direction, at the same time for the same distance
Types of Linear Motion
Rectilinear - straight line
Curvilinear - curved line
Angular movement
All point on the body move through the same ankle around the same acid of rotation
General Motion
Is combination of angular and Linear motion and is the most common, think ACL tear - femoral/tibial translation with or without plant and femoral rotation
Time
Duration of a articular event ^t
Injury implication - bone fractures vary depending on amount of force applied and duration of application
Position
orientation of the whole body or a segment of the body
Quality of description: knees are bent
Quantitative description: elbow flexed at 45*
Injury implication: injuries to the neck depends on the angular position of the neck
Position
orientation of the whole body or a segment of the body
Quality of description: knees are bent
Quantitative description: elbow flexed at 45*
Injury implication: injuries to the neck depends on the angular position of the neck
Spacial reference System
A fixed or inertial system of references
One dimension = on a line only one number is needed
Two dimensional = on a plane needs two coordinates
Three dimensiona = in space needs three coordiates
Polar Coordinate System
a two-dimensional coordinate system in which each point on a plane is determined by a distance from a reference point and an angle from a reference direction.
Pole
Reference point or origin of a point on a plane in the Polar Coordiate System
Ray
and the angle is called the angular coordinate, polar angle, or azimuth.[1] The radial coordinate is often denoted by r or ρ, and the angular coordinate by φ, θ, or t. Angles in polar notation are generally expressed in either degrees or radians (2π rad being equal to 360°).
Radial Coordinate
The distance from the pole; also called radial distance, simple radius
Radiacl coordinate
r or p
Angular coordinate
φ, θ, or t.
How iar angles in polar notation expressed?
Degrees or radians (2π rad being equal to 360°)
Displacement
Straight-line distance from starting point to ending point, or number of degrees/radians of rotation (vectors)
Injury implications of Displacement
Automobiles are designed with “crash zones” or “crumple zones” intended to displace a certain safe amount in oder to dissipate or absorb energy
Distance
The length of the entire moving trajectory covered by the motion (scalar)
Relationship between Distance and displacement
Distance and displacement may be qual in value for a given moment
Distance may be greater than displacement but the reverse is never tur
Distance and Displacement are measured in different units
False; both are measured in the same units of cm, me, km, yard
Speed
Quantifies how fast an object is moving
The distance covered divided by the time taken to cover it
Speed = (distance)/(time)
Velocity
Quantifies the rate of change in location for moving object
The displacement divided by the time taken
Velocity = (displacement)/(time)
Injury implications of speed and velocity
projectile injuries
Acceleration
The rate of change in velocity over time
A = ^V / ^t A = V2-V1 / ^t
Injury implications of acceleration
impact injuries
Brain concussive injures
Distance linear equation
s= r x θ
Velocity Linear equation
v = r x w
What must angular quantities be expressed in?
Radians
The linear quantity and radius must be in the same units of …
Length
Kinetics
Study of forces and their effects
Mass
Quantity of matter in kg
Inertia
The tendency of mass to resist changing its stat e or rest or movement
Injury implication of mass and inertia
Whiplash - head in motion tends to stay in motion while a torso movement is restated by seatbelt or seat itself
Moment of inertia (I) is the resistance to …
angular acceleration
The larger the mass =
the greater moment of inertia
The moment of inertia is dependent on
additional factors such as the distribution of mass with respect to the acts of rotation
For a single particle of mass, its moment of inertia is calculated as
I = m * r^2
Unit = kg*m^2
Calculation of a moment of inertia for the entire body =
I = some of ( initial mass * initial radius ^2)
I = m1r1^2 + m2r2^2 + m3r3^2
Calculation of a moment of inertia for the entire body =
I = some of ( initial mass * initial radius ^2)
I = m1r1^2 + m2r2^2 + m3r3^2
Force
The mechanical action or edict applied to a body or produced by the body that tends to produce acceleration
Newtons (1 kgms^-2)
What is the most fundamental element in injures?
Force
Idealized force vector
A single force vector representing the net effect of distributed forces
Internal Forces
Act within the object or system whose motion is being investigated
these forces do not produce motion to the system, but only the part it acts on
External Forces
Act on objects as a result of interaction with the environment
These forces produce motion to the system
Contact Forces
Forces that occur when two objects interacting with each other are physically in contact with each other
Non-Contact Forces
A force that can be applied without any contact between two bodies is called non-contact force
I.e: gravitational force, magnetic force
Graviational Force
Every object attracts every other object with a force directed along the line of centers of the two objects
The force is proportional to the product of their masses and inversely proportional to the square of the separation between the two objects
Friction
Component of a contact force that acts parallel to the surface in contact
- acts opposite to the motion or motion tendency
- reflect interaction between molecules in contact
- reflect forces “squeezing” surfaces together
- Acts at the area of contact between two surfaces
Static Friction
Surfaces not moving relative to each other
Maximum static friction
F(m) = maximum amount of frication that can be generated between two static surfaces
Maximum static friction
F(m) = maximum amount of frication that can be generated between two static surfaces
Dynamic Friction
F(d) surfaces move relative to each other; constant magnitude friction during motion
Also know as Kinetic friction
Always less than maximum static friction
Friction is determined by…
the frictional coefficient and normal force
F = uR
Static Friction
a force that keeps an object at rest and must be overcome to start moving the object
If a small amount of force is applied to an object, the static friction has _____ magnitude in the ______ direction
equal; opposite
Friction force
Force that acts over the area ov contact between 2 surfaces
Acts in the direction opposite of motion
Static friction opposes…
impending relative motion
Dynamic friction opposes…
relative motion
What prevents an object’s intention to move?
If the horizontal external force does not reach F(s, max), then F(s) is equal to the horizontal external force
Two components of gravitational resistance force:
Normal Force: Perpendicular to the surface and opposes penetration
Tangential (Frictional) Force: along the surface and opposes sliding
Center of Mass`
The center of mass is a position defined relative to an object or system of objects. It is the average position of all the parts of the system, weighted according to their masses.
Where is the COM in the anatomical position
Near the waist
Males: 54-57% of height
Female: 53-56% of height
Pressure
P = F/A. (N/m^2)
Force inc => Pressure Inc
Area Dec => Pressure Ince
Torque
The effect of a force9s) that tends to cause rotation or twisting about an axis of rotation
Angular corollary to force M= F*d
Concentric Torque
Went net torque are joint movement occur in the same direction
Eccentric Torque
Torque in the direction opposite joint movement
