biomechanics ch 13
static equilibrium
a motionless state
balance
a persons ability to control equilibrium
lever
a simple machine consisting of a relatively rigid barlike body that may be made to rotate about an axis
base of support
area bound by the outermost regions of contact between a body and support surface or surfaces
The ability to control equilibrium defines ____________.
balance
dynamic equilibrium
concept indicating a balance between applied forces and inertial forces for a body in motion
A concept indicating a balance between applied forces and inertial forces for a body in motion is called ________________.
dynamic equilibrium
first class lever
lever positioned with the applied force and the resistance on opposite sides of the axis of rotation
third class lever
lever positioned with the applied force between the fulcrum and the resistance
second class lever
lever positioned with the resistance between the applied force and the fulcrum
The ratio of force arm to resistance arm defines _______________.
mechanical advantage
Torque is the product of force and the perpendicular distance from the force to the axis, also known as the ___________________________.
moment arm
couple
pair of equal, oppositely directed forces that act on opposite sides of an axis of rotation to produce torque
center of mass/mass centroid/center of gravity
point around which the mass and weight of body are balanced. no matter how the body is positioned
segmental method
procedure for determining total body center of mass location based on the masses and center of mass locations of the individual body segments
mechanical advantage
ratio of force arm to resistance arm for a given lever
stability
resistance to distuption of equalibrium
moment arm
shortest (perpendicular) distance between a forces line of action and axis of rotation
reaction board
specially constructed board for determining the center of gravity location of a body positioned on top of it
fulcrum
the point of support or axis about which a lever may be made to rotate
torque
the rotary effect of a force about an axis of rotation, measured as the product of the force and the perpendicular distance between the forces line of action and the axis
A lever positioned with the applied resistance between the axis and the force is a ________ class lever.
2nd class