Quiz 2 Flashcards
Biomechanics
Describe inertia
The ability of an object to resist change (continuous movement)
(Note: The greater the mass, the greater the inertia)
What is “moment of inertia”?
The ability of an object to resist change in an angular movement
Describe the Law of Action-Reaction
For every action, there is always an equal (and opposite) reaction
(ex: if you punch a wall, it punches you back)
What does Newton’s 1st Law state?
The greater the mass, the greater the inertia (Law of Inertia)
What does Newton’s 2nd Law state?
Nothing… just know that it is the Law of Acceleration
What does Newton’s 3rd Law state?
For every action there is always an equal and opposite reaction (Law of Action-Reaction)
What are the 3 things to consider when looking at force?
- Axis of rotation
- Resistance (Gravity or weight)
- effort
Describe “torque”
“Torque” is the angular term for “force”
Describe “moment arm”
The perpendicular distance from the axis of rotation to the force vector
Differentiate between the 3 classes of levers
Class 1 Lever: Axis of rotation is in between the resistance and effort
Class 2 Lever: Resistance is in between the axis of rotation and effort (mechanical advantage)
Class 3 Lever: Effort is located between the axis of rotation and resistance
(excursion advantage)
Differentiate between vector and scalar
Vector: Must contain direction and magnitude
- Force, weight, velocity, displacement
Scalar: Contains magnitude but no direction
- Mass, speed, distance
How to calculate momentum?
Mass*Velocity
Describe “impulse” momentum
The force that provides resistance to momentum
- Can be used concentrically to generate impulse
- Can be used eccentrically to go against momentum
Differentiate between potential and kinetic energy
Potential Energy: Energy due to it’s position
Kinetic Energy: Energy due to motion
T or F? Energy can never destroyed
True
What is power?
Moving a heavy weight as fast as possible
Differentiate between the two types of bone
Cortical Bone: Dense and forms the outer layer of a bone segment
Trabecular Bone: Low density and fills the inside of a bone segment
What are the 6 types of bone fractures?
- Compression Fracture (caused by compression)
- Tension Fracture (caused by pulling at both ends of the bone segment)
- Bending Fracture (caused by bending of the bone segment)
- Shear Fracture (caused by two forces going opposite directions… one force moves the upper part of the bone one way and one force moves the lower part of the bone the other way)
- Torsion Fracture (caused by twisting of the bone segment)
- Combined Loading Fracture [caused by compression and torsion (twisting) of a bone segment]
How do you strengthen a bone?
Weight bearing exercises
(Supported by Wolff’s Law: “If loading on a particular bone increases, the bone will remodel itself over time to become stronger to resist that sort of loading)
How is “stiffness” determined?
- The force that acts on an object (stress)
- The shape of the object (strain)
ex: An object is considered stiff if a large amount of force can only cause a small change of shape
What are the 3 types of joints?
Synarthrosis: Joints that can barely move (skull)
Amphiarthrosis: Joints that can slightly move
Diarthrosis: Joints that can move freely with a certain amount of “degrees of freedom”
Degrees of Freedom (DOF): The number of axis that the joint can move around
What are the 6 types of joints?
- Plane Joint
- Hinge Joint
- Pivot Joint
- Saddle Joint
- Condyloid Joint
- Ball and Socket Joint
Differentiate between a close-packed and loose-packed joint position?
Closed-packed: Joint space is minimized
Loose-packed: Joint space is maximized
What are the 3 types of muscle fibers and their function?
Type I: Slow-twitch oxidative fibers
- High endurance, low power
Type IIa: Fast-twitch oxidative fibers
- Intermediate power and endurance
Type IIb: Fast-twitch gylcolytic fibers
- High power, low endurance
T or F? Posture muscles are more type I whereas power muscles are more type II
True
T or F? Atrophy is greater in type II muscle fibers than it is in type I
True
How do muscle neuromechanics work? provide an example
Alpha motor neurons send a signal to an axon, and the axon carries the signal to innervate muscle fibers
ex: flicking a light switch on, the current traveling through the wires, then eventually turning the lights on
T or F? Small size motor units control type I muscle fibers, medium size motor units control type IIa, large size motor units control type IIb muscle fibers
True
What does the henneman’s principle state? What is the benefit of it?
Motor units are recruited from smallest to largest (this helps preserve energy)
Explain the roll and slide of…
- convex on concave
- concave on convex
Convex on Concave: Roll and slide are opposite
Concave on Convex: Roll and slide are same
What is force decomposition?
When you see a muscle in oblique orientation, readjust it to horizontal and vertical components
