Free Body Diagrams Flashcards
What is a free body diagram?
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.
T/F There is some subjectivity (art) in drawing FBD, but there are also some rules that cannot be ignored (science)
True
How would be make a simple representation of the body?
Think of the skeletal structure and draw straight lines to represent simple bones like the arms and legs.
How are joint centres estimated?
They are represented with circles
How can we represent more complex skeletal structures like the head, chest, hips?
We can draw simple shapes.
T/F The rigid body must have a shape that is sufficient to include all points of application of all of the forces acting on the body.
True
What is important to include in your FBD?
Arms, feet
What do FBD help us focus on?
Critical joint movement and posture
What can you add in your FBD so we are able to tell the motion?
Include movement vectors
What are benefits to FBD?
- Remove all unnecessary visual information
- Focus simply on the structural movement
- Rigid segments where forces act
What are limitations to FBD?
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 centres?
- Did we get rid of or misrepresent useful information? (Represent limbs that can’t be seen in the picture as a dotted line)
T/F FBD is just another observational tool
True
T/F FBD isn’t necessary but it helps visualize underlying movement of the skeletal structure, where movement occurs, and forces act.
True
T/F We can imagine a FBD diagram during normal observation or draw a FBD on a still image to further analyze the performers action.
True
What can a vector be thought of?
- An arrow connecting two points
- They have a magnitude and direction
