Exam 1 Flashcards
Name 7 uses for biomechanics.
- skill analysis
- design of equipment
- prosthetics, adapted physical education
- sport clothing
- environmental considerations
- rehab, improving technique
- postural/gait analysis
What are the 3 sub sections (classification) of mechanics?
- rigid body mechanics
- fluid mechanics (aerodynamics)
- deformable body mechanics
What is kinematics, and how can it be broken down?
- description of motion
- linear and angular
What is kinetics, and how can it be broken down?
- forces that cause motion or are caused by the human body
- linear: motion in a straight line
- angular: motion around an axis
Why is biomechanics important for coaches?
to gain a basic understanding of mechanical principles that helps produced an improved performance
Define technique.
the pattern and sequence of movements that the subjects use to perform a movement skill (or sports skill)
Name 3 influences that technique can come from.
- always done it that way
- trial/error
- pros do it that way (not always good)
Name 6 reasons why technique changes.
- equipment
- age of the performer
- condition/experience
- psychological reasons
- science
- genetics
What is a cardinal plane?
- midsagittal, frontal, horizontal planes
- passes through the centre of gravity of the body
- all planes at 90 degrees to each other (perpendicular)
Motion within the frontal (coronal) plane corresponds with which axis?
anterior/posterior (A/P) axis
Motion within the sagittal plane corresponds with which axis?
transverse (frontal) axis
Motion within the horizontal (transverse) plane corresponds with which axis?
longitudinal (vertical) axis
Motion within the oblique plane corresponds with which axis?
oblique axis
A slapshot is a skill conducted in what plane and what axis?
- oblique plane
- oblique axis
A tennis serve is a skill conducted in what plane and what axis?
- sagittal/oblique plane
- transverse/oblique axis
A back flip is a skill conducted in what plane and what axis?
- midsagittal plane
- transverse axis
A upper cut is a skill conducted in what plane and what axis?
- sagittal/oblique plane
- transverse/oblique axis
A discus throw is a skill conducted in what plane and what axis?
- horizontal plane
- longitudinal axis
A underhand baseball pitch is a skill conducted in what plane and what axis?
- sagittal plane
- transverse axis
Lateral raises is a skill conducted in what plane and what axis?
- frontal plane
- A/P axis
What are the 8 major body segments?
- head and neck
- trunk
- arm
- forearm
- hand
- thigh
- leg
- foot
What is dorsiflexion?
pulling the top of the foot to the shin; specific to ankle
What is plantar flexion?
pulling toes to the ground; specific to ankle
Define rotation.
- movement of a segment around long axis
- usually carries the name of the segment being rotated (ex. trunk rotation)
- the rotation of appendages usually occurs in it’s own axis
What is circumduction?
- primarily at the shoulder and hip
- makes the shape of a cone
Name 7 movements that occur at the shoulder joint.
- flexion/extension
- circumduction
- adduction/abduction (horizontal and diagonal)
- elevation/depression
- protraction/retraction
- scapular rotation (up/down)
- scapular rotation (medial/lateral)
Define force.
- a push or a pull
- anything that causes change in motion or shape of an object
Force is a vector quantity, which has 4 characteristics:
- magnitude
- direction
- point of application
- line of action
Name the 3 types of forces.
- motive (propulsive) vs. resistance
- internal vs. external
- contact vs. non-contact
Give 5 examples of forces.
- gravity
- air resistance
- friction
- contact with the ground
- contact with another body
1 newton =
1 newton = 1 kg x 1 m/s^2
N = kg x m/s^2
On earth, a mass of 1 kg exerts a force of approximately ____ N downwards.
9.81 N
Define mass.
- quantity of matter
- substance
Define weight.
- measure of gravitational force
- result of the force of gravity
Weight and mass are ______, but not ____.
- proportional
- equal
How do we calculate weight?
W = m x g W = \_\_\_\_\_N (kg x 9.81 m/s^2)
Define equilibrium.
- the sum of all forces are balanced
- describes a action or state
Define balance.
maintaining control of the body
Define stability.
- capacity of an object to return to equilibrium
- describes a characteristic
What subdivisions can stability be broken into?
- static or dynamic
- linear or rotary
What is centric force, and what movement does it cause?
- application of a force through the centre of gravity of an object
- causes translation only (linear, no rotation)
What is off-centre eccentric force (torque), and what movement does it cause?
- application of a force away from the centre of gravity of an object
- causes rotation around a fixed point
What is the centre of gravity (CoG)?
- single point where sum of all the forces are balanced
- centre point of weight distribution
- a.k.a. equilibrium point, balance point, pivot point
What is the centre of mass (CoM)?
the midpoint of an object where there is an equal distribution of mass but without regard for gravity
Where is the centre of gravity located in humans?
- males: 56-57% of standing height
- females: 2-3 inches below, 55% of standing height
- varies depending on position of the body… it doesn’t even have to be on the body
Why is there a difference in the location of centre of gravity between males and females?
men tend to have larger shoulders and smaller hips
If someone raises their arms, their centre of gravity would (rise/fall).
rise
What is the line of gravity (LoG)?
- lateral balance of mass within the object (in equilibrium)
- the line from the centre of gravity downwards towards the Earth’s centre
What is the base of support (BoS)?
- the position of, distance between, or the amount of supporting surface
- number of points of contact with the ground
Name the 7 EBS principles of maintenance.
- lower CoG = higher stability
- greater stability is obtained if the BoS is widened in the direction of the line of force
- increased friction = increased stability (linear)
- position the LoG within the BoS
- more mass = more stability (linear)
- in a vertically segmented body, stability increases when the CoG of each weight-bearing segment is centred over the BoS
- regaining equilibrium is based on the same principles as maintaining it
What are co-linear forces?
forces in the same plane (parallel, can be in same or different directions)
What are concurrent forces?
forces applied at the same time in different directions
What is quantitative analysis?
- numbers
- needs to be humanly possible (human elements)
- harder to interpret
What is qualitative analysis?
- words describing motion
- easier to describe, starting point, used by coaches
What is the difference between distance and displacement?
- distance is a scalar measurement
- displacement is a vector measurement
What is a scalar measurement?
- physical quantity
- only magnitude
- no direction
Give 3 examples of scalar measurements.
- distance
- speed
- mass
What is a vector measurement?
- physical quantity
- direction and magnitude
Give 2 examples of vector measurements.
- displacement
- velocity
What is acceleration?
- change of velocity over time
- rate of change of velocity
What are the 5 key variables in motion of a body?
a- acceleration t- time of motion/flight d- distance travelled/range Vi- initial velocity Vf- final velocity
Name the 3 kinds of projectiles.
- vertical
- horizontal
- oblique
What are 3 things to consider with regards to projectiles?
- time of flight
- maximum height reached (zenith, apex)
- horizontal distance travelled (range)
Name 4 aspects of ideal vertical projectiles.
- gravity acts the same on all objects
- time up = time down
- velocity at its apex is zero; Vi = 0
- the value of acceleration due to gravity is 9.81 m/s^2 or 32.2 ft/s^2
Name 2 factors that affect the flight of vertical projectiles.
- force of gravity: g = ?
- initial velocity of the object
Name 2 factors that affect the flight of horizontal projectiles.
- force of gravity: g = ?
- initial projection velocity of the object
- these 2 factors act independently of each other (it doesn’t matter what force the object is projected at)
If an object is horizontally projected at the same time that a duplicate of the object is vertically dropped, which object will land first?
both will land at the same time
In horizontal projectiles, how is height related to range?
as height increases, range increases (proportional)
In horizontal projectiles, how is velocity related to range?
as velocity increases, range increases (proportional)
What is the most common kind of projectile?
oblique projectiles
What is an oblique projectile?
an object projected at an acute angle will follow the path of a parabola
What are the 3 variables of an oblique projectile?
- time
- height
- range
What do the 3 variables of an oblique projectile depend on?
- gravity
- velocity of projection
- angle of projection
How does angle of an oblique projectile effect range?
- as the difference between release and landing heights increases, the ideal angle of projection decreases (less angle means more range)
If the release and landing heights are the same, the ideal angle for maximum range is __ degrees.
45 degrees
What is the difference between instantaneous and average velocity?
instantaneous velocity can illustrate immediate problems while average velocity balance out the good and bad
For any projectile, the following can be determined:
a- acceleration t- time of flight d- distance travelled Vi (u)- initial velocity Vf (v)- final velocity
