Week 1 Flashcards
Define biomechanics
The application of mechanics to the human body
Define kinematics
Branch of mechanics that describes the motion of the body without regards to the forces or torques that may produce the motion
Kinetics definition
Branch of mechanics that describes the effects of forces and torques on the body
What are some methods of analysing biomechanics
Observation Anthropometry 3D motion capture Force plates/transducers Pressure sensors EMG-surface/fine wire
Biomechanics parameters that describe movement
Scalar
Vector quantities
Define scalar quantities
Represented by magnitude
E.g. Mass, time, length, speed
Define vector quantities
Represented by magnitude and direction
E.g force, moment, weight, velocity
What are degrees of freedom used to indicate
Planes of angular motion at a joint
Eg: flexion/ext
Int/ext rotation
Ab/adduction
Newton’s first law of motion
Every object in a state of rest or uniform motion will remain in that state unless an external force is applied to it
Newton’s second law of motion
The relationship between an object’s mass m, it’s acceleration a, and the applied force F is
F=ma
Newton’s third law of motion
For every action there is an equal and opposite reaction
Formula for torque
Torque = F x r (moment)
Pressure formula
Pressure = force/area
Work formula
Work= Force x Displacement
What unit is work calculated in
Joules (J=Nm)
Power Formula
Work/Time
What is power measuring
Measure of the rate of work performance
Stress formula
Stress = force/area
Strain formula
change in length/ original length
Define an elastic material
a loaded material,upon unloading returns to it’s original shape
Define a plastic material
a loaded material undergoes deformation and does not return to its original shape when loading is removed
At what point does elastic change to plastic?
at the yield point
What is the stress that causes this called
yield strength
What is the ultimate tensile stress/strength
largest stress the a material can withstand before breaking
defines point of failure
What is Young’s modulus?
modulus of elasticity, or material ‘stiffness’
- how much a material strains (stretches) when it is subjected to specific stress
- how much stress builds in a material when it is strained (stretched ) by a specific amount.
What is Poisson’s ratio?
Ratio of lateral strain and axial strain
What are viscoelastic materials
Have properties associated with the stress-strain curve change as a function of time
What is creep?
progressive strain of a material when exposed to a constant load over time
e.g. change of height during the day due to compression on intervertebral discs
Clinical scenario involving creep
stretch of vertebral ligaments with prolonged sitting
