Lecture 3- Motion I/II Flashcards
Magnitude only
Scalar quantities
Magnitude & Direction (force, velocity: e.g. 1.5 m/s to right)
Vector quantities
g =
9.81 m/s2,
m • g,
W
Does MA (Moment Arm) of a muscle changes with Joint Angle?
Yes
= F * MA
Torque
A sketch of the outlined shape of the body or body segment, which represents it, as being isolated from its surroundings with all forces and torques that the surroundings exert on the body
Free Body Diagram
condition in which an object is at rest if originally at rest, or has a constant velocity (linear and angular) if originally in motion.
Equilibrium of the Force System (Statics)
Lever Class
E –>F–>Load
First
Lever Class
E –>Load–>Fulcrum
Second
– your gastrocnemius
Lever Class
Fulcrum –> Effort –> Load
Third
Biceps
The ability of the tibialis posterior to lift the arch depends
Retinaculum ??
Property of the mass.
Inertia
Property of the mass and its distribution with respect to the axis of rotation
Moment of Inertia
force x distance x cos θ
Work
Capacity to perform work
Energy
Energy due to an objects motion (½ mv2)
Kinetic
Energy due to an objects position (m g h)
Potential / Gravitational
Energy stored by compression or stretching
Elastic
The RATE that work is done
Power
Work / time interval –or– Force x Velocity
Power
Property of a moving body
Momentum
Mass x Velocity
Both Mass and Velocity affect the time or the distance it takes to stop a moving object
Momentum
Change of Momentum
Force x Time interval
Impulse
Reduction of Momentum
Shock Absorption
) accounts for net forces generated by “bone-on-bone” contact
Joint reaction force (JRF)
What contributes to JRF?
muscle force (due to muscle activity)
gravity related forces (mass of whole body or body segments)
forces due to motion (inertia)
ligamentous
