Bio-mechanics 1 Flashcards
What is the law of inertia?
an object at rest tends to stay at rest and an object in motion tends to stay in motion unless there is a force changes it current status
What is inertia?
ability of an object to resist change
greater the mass, greater the inertia
ex) Shaq vs baby
What is moment of inertia?
ability of object to resist change in angular motion
I= mr^2
I= moment m= mass r= radius of rotation
If an ice skater is spinning on ice and brings arm close to body what will happen?
moment of inertia will increase b/c R will decrease
Law of Acceleration
F= M*A
What is the difference between mass and weight?
mass= weight w/o gravity
weight= weight w/ gravity
What is newton’s third law?
for every action there is always an equal and opposite reaction
if you punch wall, wall will punch back
What two coordinate systems are used in force analysis?
Global and relative
What does X and Y represent in global?
X= the AP direction of the space
Y= represents vertical direction of space
What is relative coordinate system?
X= parallel to body segment we are interested in
Y= perpendicular to the X
What are the three features of force?
it has an application point, magnitude and direction
Where is the application point?
for the muscle: the PA or DA
for gravity: the center of mass of body segment
What is a vector?
have both magnitude and direction
What is force decomposition?
when force is neither parallel to X or Y, it must be analyzed separately
What is torque?
Force X moment arm
angular term for force
