Module 5/6: Biomechanics of human movement Flashcards
Describe each of Newtons laws:
Law of Inertia: an object will remain at rest unless acted on by an external force
Law of acceleration: change in momentum is proportional to the force applied and in the same direction
Law of action: every action has an equal and opposite rxn
What is the difference between a 1D and 2D force system?
1D - forces act in the same plane and line of action
2D - forces act in the same plane but diff lines of action
Give examples of 1D and 2D force systems?
1D - collinear
2D - coplanar (same plane but not same line) , parallel (forces in parallel to each other), orthogonal ( forces are perpendicular), concurrent (forces originate from the same point)
What are the differences between static and kinetic friction?
static is between bodies that are not moving, kinetic is between two moving bodies
What are some keys to remember in regards to elastic forces?
they are in the opposite direction of the deformation
- materials will deform depending on the load being applied and the material stiffness
Define moment:
turning movement resulting from a force applied at a distancce from the axis of rotation
Describe the differences between the types of levers in the body. Give examples.
type 1 - axis is between the force and the resistance (head on the neck)
type 2 - resistance is between the force and the axis (going onto tippy toes)
type 3 - force is between the axis and the resistance (bicep curl)
Explain the keys in order for a mechanical advantage to be obtained?
force arm is longer than the load arm
Describe the value of having a speed advantage and how this is obtained?
if a system is at a mechanical disadvantage (MA<1) it has a speed advantage and creates increased angular displacement and speed distally (force arm is shorter than the load arm)
What are the keys to remember when discussing moment of inertia?
it is harder to move a body part that has increased mass or a body part that is farther away from the axis of rotation
What are the differences between COG, COM and LOG?
COG - center of a body where the weight is considered to be concentrated
COM - point about which the mass of an object is evenly ditrubuted
LOG - projection of COG to the ground
What are the differences in the types of work that are done with the different types of contractions?
Concentric - positive work (muscle shortens)
Eccentric - negative work (muscle lengthens)
Isometric - no work (length doesn’t change)
What is the difference between hydrostatics and hydrodynamics?
Hydrostatics: study of effects of force and pressure on a fluid at rest
Hydrodynamics: fluid in motion
Describe hydrostatic pressure in regards to human movement?
a pressure exerted in all directions that is related to the weight of the fluid (increased pressure with increased depth)
At what density does a human body need to be in order to float?
< 1 (avg is 0.86-0.97)
Describe buoyancy and how it can be used for rehab?
upwards force fluid exerts on a body in water
can be used to help push a body part upwards rather than having to rely solely on the muscle action to do so
