Wk 6 - Torque, levers, COG Flashcards
Clock wise torque =
positive motion
Counter clockwise torque =
negative motion
Torque is the _____ _____ of a force about an axis of rotation
turning effect
Torque = ___ x ___
T = F x perpendicular distance (d or s)
a ______ is the perpendicular distance from an axis to the line of action of a force
moment arm
A moment arm is the…
is the perpendicular distance from an axis to the line of action of a force
Is torque a force?
No
Torque is the _____ of a force causing ____ about an axis
effectiveness, rotation
Power =
F x d / t
Fulcrum (F) is the..
point of suspension or axes of rotation (point where it pivots)
Effort (E) on lever is …
the point where force is applied
Load (L) on lever is ….
where load or resistance is applied
First class lever system
F ulcrum in the middle of E and L. (see-saw like. e.g. head and neck)
Second class lever system
Load in between fulcrum and effort (wheel barrow. e.g. calf raise)
Third class lever system
Effort between load and fulcrum (elbow joint, most prominent in the body)
Torsional lever (fourth class)
Load in directly above fulcrum, force causes rotation
Mechanical advantages is defined as…
ratio of the effort arm to the resistance arm (MA = effort arm / resistance arm)
If the fulcrum to load distance is > fulcrum to effort distance =
provides a distance / speed advantage (load moves further than effort in same time)
If the fulcrum to load distance is < than fulcrum to effort distance =
provides a FORCE advantage (load is greater than the effort applied)
If mechanical advantage > 1 =
Force advantage
If mechanical advantage < 1 =
Speed / distance advantage
COG is the point where…?
a body’s weight is equally balanced in all directions
Stability -
resistance to disruption of equilibrium
Balance -
ability to control equilibrium
If displacement is due to work done by force and returns to original position = this is..?
Stable equilibrium
If displacement is increased =
Unstable equilibrium (person doing head stand)
If displaced and moves to new position =
neutral equilibrium (ball on flat surface with force applied)
increased weight, _____ stability
increased weight, increases stability
_______ friction, increases stability
increased
increasing size of base of support = _________ stability
Increased stability
