Foundations Flashcards
Why is the right-hand rule useful?
- tells us the orientation of the 3rd axis if we know the directions of the 1st and 2nd axes
- tells us the directionality of moments
What axes form the Frontal (Coronal) plane?
Vertical & mediolateral
What axes form the Sagittal plane?
Vertical & anteroposterior
What axes form the Transverse plane?
Mediolateral & anteroposterior
What axis does the Frontal plane rotate about?
Anteroposterior
What axis does the Sagittal plane rotate about?
mediolateral
What axis does the Sagittal plane rotate about?
vertical
What is the difference between kinematics and kinetics?
Kinematics is the description of motion & Kinetics is the description of forces
Define:
Displacement
Velocity
Acceleration
Angular Displacement
Angular velocity
Angular acceleration
(kinematics terms)
Displacement = change in distance
Velocity = change in distance/change in time
Acceleration = change in vel/change in time
Angular displacement = change in angle
Angular velocity = change in angle/change in time
Angular acceleration = change in angular vel/change in time
What is the eq for force and the units?
F = mass * accel
Units: Newton
What is the eq for moment (torque)?
Moment (torque) = Force * moment arm (ma) = Fd
Define “Moment Arm”
PERPENDICULAR distance btwn line of action of the force and the axis of rotation
T or F: Moments have magnitude and direction?
True.
CCW = +
CW = -
Compare scalar and vector quantities
Scalar: have mag only, can be + or -, add algebraically if same unit)
Vector: mag & direction, usu noted with –> or underline, add by parallelogram (A+B = R)
Roughly, where should the center of mass be in static stance?
S2 vertebra
Does COM shift with weight distribution?
Yes.
What is the center of gravity?
balance point for an object
What is Newton’s 1st law?
Law of Inertia:
An object at rest will stay at rest AND an object in motion will stay in motion unless acted on by an unbalanced external force
Is a force-couple equivocal to static equilibrium?
No
What is static equilibrium?
Sum of forces = 0
All forces and moments acting on a system sum to 0
What is Newton’s 2nd law?
Law of Acceleration:
Acceleration is produced when a force acts on a mass (F = ma)
Larger mass requires larger force to accel or decel
What is Newton’s 3rd law?
Law of Reaction:
For every action, there is an equal and opposite reaction
Reaction force acts in the opposite direction, along the same line as the action force
What is a force-couple?
PARALLEL forces w/ EQUAL magnitudes and OPPOSITE directions
Think: steering wheel (where the parallel forces are separated by a distance)
What is translational motion and what are the 3 types of force systems?
Forces acting at 1 location
- Collinear force system (tug a war)
- Concurrent force system
- Pulley force system
What is Class 1 Lever?
See-saw: External force (load) and internal force (muscle) are on OPPOSITE sides, w/ fulcrum in middle
For a Class 1 Lever, how does the MAmuscle compare to the MAexternal?
Can be >, <, or =
What is an anatomical example of a Class 1 Lever?
Holding head in a neutral position while standing
Triceps muscle
What is a Class 2 lever?
Wheelbarrow: Fulcrum and internal force (muscle) are on OPPOSITE sides with the external force (load) in the middle
For a Class 2 lever, how does the MAmuscle compare to the MA external?
MAmuscle > MAexternal
What is an anatomical example of a Class 2 Lever?
Toe raise
Why does a Class 2 lever provide great mechanical advantages for the body?
Because you can lift very heavy loads through short distances.
What is a Class 3 lever in relationship between external force (load), fulcrum, and internal force (muscle)?
Fulcrum and external force (load) on Opposite sides with internal force (muscle) in middle
What is an anatomical example of a Class 3 lever?
Biceps lifting a dumbell
(Fulcrum = elbow
For a Class 3 lever, how does the MAmuscle compare to the MA external?
MAmuscle < MAexternal
Do class 3 levers have ow or high mechanical advantage?
Low
What is the benefit of a class 3 lever?
Small shortening of muscle causes large movements of the segment
Therefore, they are able to produce large amounts of movement with low mechanical advantage.
Which class of lever is most common in the body?
Class 3
External rotation of the shoulder is motion that occurs in the ___ plane about the ___ axis
Transverse, vertical
What are examples of scalar quantities?
mass, distance, speed
What are examples of vector quantities?
weight, displacement, velocity
Abduction of the hip is a motion that occurs in the ___ plane about the ___ axis
Antero-posterior axis
