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