Levers Flashcards
What 3 actions may a lever be used for?
INCREASE FORCE \+ CHANGE DIRECTION OF FORCE \+ GAIN DISTANCE
Name the 4 components of lever systems, and how they compare with body mechanics?
RIGID BAR - BONE
FULCRUM - AXIS
MOTIVE FORCE - MUSCLE WORK
RESISTIVE FORCE - WEIGHT/GRAVITY
The distance from motive force to the fulcrum is known as: __________ arm.
FORCE ARM
The distance from the resistive force to the fulcrum is known as: __________ arm.
RESISTANCE ARM
The 3 types of levers are classified according to the relative positions of which 3 factors?
AXIS + MOTIVE FORCE + RESISTIVE FORCE
In a _________ __________ lever, the resistance arm and force arm are on opposite sides of fulcrum.
FIRST CLASS
ie teeter totter, suboccipital mm
Name the most versatile type of lever system?
FIRST CLASS
ie teeter totter, suboccipital mm
How can you improve the first class lever system to gain mechanical advantage?
FORCE ARM BECOMES LONGER
In a _________ __________ lever, both the resistance arm and force arm are on the same side of fulcrum.
SECOND CLASS
ie wheelbarrow, posterior leg mm
In a second class lever, the force arm is ____________ than the resistance arm, and force and resistance move in the _________ direction.
LONGER
+
SAME
Why is the second class lever system mechanically disadvantaged?
MOTIVE FORCE
must always move a greater distance than
THE RESISTANCE
Name the most common lever system?
THIRD CLASS
shovelling manure, hamstrings, quads, iliopsoas
In a _________ __________ lever, both the resistance arm and force arm are on the same side of fulcrum.
THIRD CLASS
In a third class lever, the force arm is ____________ than the resistance arm.
SHORTER
How does a third class lever provide advantage as a lever arrangement?
SPEED AND DISTANCE
of
ROM TRAVELLED
