Biomechanics midterm Flashcards
what is the study of systems in constant motion?
statistics
what is the study of systems subject to acceleration?
dynamics
what is the study of the appearance or description of motion?
kinematics
what is the study of the actions of forces?
kinetics
what movements occur in the sagittal plane?
flexion, extension, hyperextension, dorsiflexion, plantar flexion
what are the 3 reference planes of movement?
sagital
frontal
transverse
what is angular motion?
rotation around an axis
what is linear motion?
motion along a line
what is the cartesian coordinate system?
x,y,z coordinates
what is the actual distance travel called?
distance
what is the distance measured in a straight line from start to finish called?
displacement
what is the rate of change in location?
velocity
what is velocity’s equation?
velocity = Displacement/Time
what is the rate of change in linear velocity?
acceleration
what is accelerations equation?
Acceleration = Change in Velocity/Time
what 3 factors affect shot-put distance?
projection angle
projection speed
relative projection height
what is the law that says a body will maintain a state of rest or constant velocity unless acted on by an external force that changes the state
law of inertia
what is the law where a force applied to a body causes acceleration of that body
law of acceleration
what is the law of reaction?
for every action, there is an equal and opposite reaction
what is friction?
force acting over the area of contact between two surfaces
what is the quantity of motion possessed by a body
momentum
what is the product of a force and the time interval over which the force acts; causes momentum
impulse
what is elastic impact?
the velocity of the system is conserved
what is plastic impact?
there is a total loss of system velocity
how does height affect PE
increasing height will increase PE
how does velocity affect kinetic energy
increasing height will increase KE???
what is a radian?
size of an angle subtended at the center of a circle by an arc equal in length to the radius of the cirlce
What happens to linear velocity as the radius of an angular movement is increased?
The greater the radius between a given point on a rotating body and the axis of rotation, the greater the linear distance traveled by that point during an angular motion.
what is the moment of inertia?
inertial property for rotating bodies*
represents resistance to angular acceleration
based on both mass and the distance the mass is distributed from the axis of rotation
what is the distance from the axis of rotation to a point where the body’s mass could be concentrated without altering its rotational characteristics
radius of gyration
what is the principal of angular conservation of momentum
total angular momentum of a given system remains constant in the absence of external torques
what is the law of angular intertia
a rotating body will maintain a state of rest of constant rotational motion unless acted on by an external torque that changes the state
Linear kinematic quantities
mass (m)
force (F)
momentum (M=mv)
impulse (Ft)
Angular kinematic quantities
moment of inertia
torque (T=Fd)
angular momentum
angular impulse
for every angular action, there is an equal and opposite angular reaction
angular law of reaction
when one body exerts a torque on a second, the second body exerts a reaction torque that is equal in magnitude and opposite in direction on the first body
angular law of reaction
what is the scapulohumoral rhythm?
a regular pattern of scapular rotation that accompanies and facilitates humeral abduction
name the muscles that contribute to flexion at the glenohumeral joint
anterior deltoid
clavicular pectoralis major
assisted by: coracobrachialis, short head of biceps brachii
name the muscles that contribute to extension at the glenohumeral joint
sternal pectoralis major
latissimus dorsi
teres major
assisted by: long head of triceps brachii
what is the difference between velocity and acceleration
Velocity is the rate of displacement and acceleration is the change in velocity
how could you cheat in weight training
using momentum: for example, you can throw your hips forward and back to increase ability to bicep curl heavier weights
what is the relative projection height?
difference between projection height and landing height
why does a diver tuck?
It will increase the rate at which they rotate. When they open back up it slows it down. When angular momentum is conserved, there is a tradeoff between moment of inertia and angular velocity. (Tuck position = small I, large ) (Extended position = large I, small )
what is the primary purpose of the antagonist muscles?
opposes/reverses movement regulation of contraction
help to protect the joint
what is gait
single sequence of functions by one limb
describe center of mass
midway between the hips
define stride length
foot to same foot
define step length
points of heel contact of the opposite foot
6 key variables in gait analysis
pelvic rotation pelvic tilt knee flexion ankle mechanism foot mechanism lateral displacement of body
what is the psoas paradox
putting tension on the outside ligament
normally flexes the spine but under 2 circumstances: hip flexion against a heavy resistance and inadequate strength of the spinal flexors the psoas will extend the spine
what is a cadence
normal pace: 100-115 steps per minute
1 newton = …
250 dynamic pounds
torque
rotation around a joint
factors affecting muscular force generation
isometric contraction
as load increases, concentric contraction velocity slows to 0 at isometric maximum
how do we measure muscular strength
the component of muscle force that produces torque at the joint is directed perpendicular to the attached bone
what factors affect muscular strength
tension-generating capability of the muscle tissue, movement arms of the muscles crossing the joint
what is muscular power?
product of muscular force and the velocity of muscle shortening
what is muscular endurance?
ability of muscle to exert tension over a period of time
what is the effect of muscle temperature (warm up)?
the speeds of nerve and muscle function increase
