Midterm 1. Flashcards
Frame of Reference to Projectile Motion
4 Task Model
Phases of Qualitative Analysis
- Preperation
- Observation
- Evaluate/Diagnosis
- Intervention
Preparation
1.Requires tools to properly observe and evaluate a movement task
-. Understanding how to observe movement (frame of reference, anatomy,
vectors)
- Understand mechanical principles to describe movement (Mechanics)
- Knowledge of skill specific considerations
- . Goal of the movement (critical features)
- . Knowledge of performers (specific, general; amateur, professional)
- . Observational bias
- . Knowledge of effective and appropriate instruction - Develop a systematic STRATEGY for observation,
evaluation/diagnosis and intervention
How to Observe Movement (4 Observational conditions)
- Frame of reference
- Free body diagrams
- Vectors
• How to visualize forces and movement - Qualitative Anatomical Assessment
• Basic Functional Anatomy
Frame of Reference (FOR)
A way to describe an objects position in space and whole body
orientation alone and with respect to external landmarks
Types of Frame of Reference (FOR)
- Egocentric ( local)
- planes
- up/down
- right/left
- front/back - Global
- in a soccer field
Plane
is a fundamental two-dimensional
object
Planes - Consider as an observer and a performer
Mid-Frontal - focuses on Abduction and Adduction as it allows us to view the anterior and posterior (dorsal) surface of the body (Also Coronal) - Perpindicular to Sag.
Mid-Saggital- focuses on flexion / extension as it allows us to view the sides of the body ( also midline/median plane). ANY PLANE PARRALEL TO MID-SAG PLANE IS JUST SAGGITAL/PARA-SAGGITAL
Transverse - focuses on rotation as it allows us to view the top down / bottom up view of the body.
Axis
Z-axis (measure of up and down)
-Intersects Saggital and Frontal planes
Y-axis (measure of left / right)
-Intersects Frontal and Transverse planes
X-Axis (measure of front/back)
-Intersect Saggital and Transverse planes
Parallel Axis - Can be used during movement to show how body is bending
Aids in alignment of body to picture parallel lines running shoulder to shoulder / hip to hip / etc.
- used in the planes for posture abnormalities
- looks for asymmetry
Frontal - lowered shoulder/ hip
Transverse - forward shoulder /hip
Saggital - pelvic tilt
Pronated (inward) / Supinated (outward roll) ankles
Free Body Diagram
-A free body diagram is an isolated
drawing of an object that is assumed to
be rigid.
-simplifications of the actual situation
but retain all of the characteristics that
are relevant.
-Therefore, there is some subjectivity
(art) in drawing a free body diagram but
there are also some rules that cannot be
ignored (science)
How to Draw a FBD
Think of Skeletal structure. Use Triangles as shoulder and hip girdle Estimate Joint centers Establish COG Establish Forces and Resulting forces
Pros / Cons of FBD
Pro:
Remove all unnecessary visual information
• Focus simply on the structural movement
• Rigid segments where forces act
Con:
Perspective
• What plane is the movement in?
• Depth
• Is each limb represented well by the 2D stick figure
• Range of motion (neck, spine, radius, ulna, ankle)
• Subjectivity
• Did we get the right joint centers
• Did we get rid of or misrepresent useful information?
Vector (3)
A thing with
• Direction- Where the arrow points
• Magnitude - length of the vector
• Point of application
Force
Simply defined a force is a push or a pull.
• is a vector quantity (Magnitude / Direction / Line of Action)
- POINT OF ACTION
• Can cause a change in the state of motion of an object.
• Can either accelerate/decelerate or deform an object
• come in pairs: action and reaction
Internal Force
act within the object or system that
is being studied
Internal pulling forces are
tensile forces
(like pulling on a rope, remember muscles are contracting)
• When you land from a jump there is a force from your lower leg on your upper leg through your knee and an equal and opposite force from your upper leg to your lower leg through you knee
Compressing Forces
Internal pushing forces are compressive forces ( knee joint)
Think of an object being
compacted.
What Happens When Forces Exceed Structure Capabilities
When the tensile or compressive forces on a structure are greater than the structure can withstand the structure will fail. When this occurs you have pulled muscles, broken bones, ruptured tendons.
External Forces (2 types)
• Forces that act on an object as a result of the
surroundings.
• Contact and non-contact
• Contact forces • Occur between objects in contact with each other • Solid or fluid • Air resistance and water resistance are fluid contact forces.
- Non-contact forces
- Gravity
- Magnetic
- electrical
Gravity
-Also known as our Weight
• We have to exert force to stand. • We feel pressure on our bodies when we sit or stand • Gravity is a non-contact force that causes us to accelerate towards the earth. Because of this we end up contacting the earth and having to exert force to overcome the pull of gravity
Normal Force
The normal force is the reaction force from the surface acting on the block that is equal and opposite to the component of gravity acting perpendicular to the surface
Friction
Friction force is required to be
equal and opposite of the
parallel force or the block
would slide down the slope
Friction force is proportional to
the normal force and acts
perpendicular to it.
-Is Necessary for motion-
Coefficient of Friction
• The coefficient of friction is related to the interaction of the surface
molecules
• Fr = uN
• Where u is the coefficient of friction and N is the magnitude of the
normal force
Static Friction
Static friction occurs when two objects in contact are not moving
relative to one another.
• The force of friction is equivalent to the external force until the object
begins to move
Dynamic Friction
• Dynamic friction occurs when the two objects in contact begin to slide
relative to one another. (sliding/kinetic friction)
• Dynamic friction is less than maximum static friction.
• It is easier to keep an object moving on a surface than to start it
moving.
