week 5 Flashcards
What is the first step in drawing a Free Body Diagram (FBD)?
Isolate the body (object, system) from its surroundings
What are the two types of external forces in Free Body Diagrams?
- Contact forces
- Non-contact forces
Where are contact forces drawn in Free Body Diagrams?
At the point of contact
Where are non-contact forces considered to act in Free Body Diagrams?
At the centre of mass
What must be selected for identifying positive and negative forces in Free Body Diagrams?
A coordinate system
What does a Free Body Diagram (FBD) represent?
All the external forces acting on a body
In Free Body Diagrams, how are forces represented?
As vectors
What does the size and direction of the arrow in a Free Body Diagram represent?
The size and direction of the force
What is the center of gravity (CG) in relation to the human body?
The point where all mass is concentrated
What is the significance of the center of gravity in human movement?
It simplifies the analysis by replacing all forces with one resultant force
What does stability refer to in biomechanics?
The ability of a body to maintain its static equilibrium posture
What are the three types of equilibrium in the context of stability?
- Stable equilibrium
- Unstable equilibrium
- Neutral equilibrium
What is stable equilibrium?
If a small perturbation is applied, the object tends to return to its original position
What is unstable equilibrium?
If a small perturbation is applied, the object tends to accelerate away from its original position
What is neutral equilibrium?
An object neither returns nor accelerates away from its original position after a small perturbation
Define base of support.
The area made with the part of the body touching the supporting surface
What factors affect balance?
- Position of CoG with respect to the base of support
- Position of the line of gravity relative to the base of support
- Size of the athlete
To increase stability against a perturbing force, where should the line of gravity be moved?
Towards the base of support
How can mobility be initiated quickly?
By positioning the CoG close to the edge of the base of support
What does equilibrium describe in the context of physics?
The state of a system that is not changing its speed or direction
What is the weight of a body in relation to particles?
The sum of all attractive forces acting towards the center of the earth
What should be considered when drawing a Free Body Diagram for a book lying on a table?
- Reaction Force from table
- Weight of book
What teaching implication is suggested for balance activities?
Start with low CoG and large bases of support
