Biomenchanics exam #1 (Terms+others) Flashcards

Push or pull on an object

• Act within an object or system whose motion is under investigation
• Forces come in pairs (action and reaction)

When pulling forced act on the ends of an internal structure

When pushing forces act oj the ends of an internal structure

Act on an object as a result of its interaction with the environment surrounding it (when two objects touch)

W = m*g

w (newtons)= m(in kilograms)*g(9.81m/s^2)

linear motions in which all parts of a rigid body move parallel to & in the same direction as every other part of the body

• motion in which a (assumed) rigid body moves in a circular path around some pivot point,
• thus the entire body moves in the same angular direction & across the same number of degrees

active or passive

the number of independent directions of movements allowed at a joint

3 degrees for 2 cardinal planes

1. roll
2. slide
3. spin

• As primary movement of bone is to rotate across another bone’s surface
• concurrent but equal + opposite side

• Spinning of one articular surface on another
• NO SLIDE

opposite

same

• at end range = close packed
• provide more stability

The study of mechanics that describes the effect of forces on the
body

• all points on a body/object move in a straight line.
• Direction of motions& orientation of object do not change.
• All points on object move the
  same distance.

• all points on a body or object move
• orientation does not
  change & all points move the same distance
• path the object follows is
  curved.

• rotation/rotary motion
• More numerous than linear motion (human movement)

• Combination of angular motions producing linear motions of multiple body parts

• vector quantity
• has direction & magnitude

• rate of motion
• AVG= d/change in time

• rate of motion in a specific direction
• AVG= velocity(or d)/change of time

• v= d/change of time
• change of t= d/velocity
• 16.8m/47.163(m/s)= 0.356 seconds

• L = linear momentum
• m = mass
• v = instantaneous velocity
• L constant => sum of forces = 0

momentum is conserved (transferred) and no energy is lost

momentum is conserved but energy is lost

the product of force and the time the force acts

• T= F*r
• F = force
• r = moment arm (perpendicular distance from axis of rotation)

• dependent upon height of center of gravity, size of base of support, and the weight of an object

sum of force

act through the center of gravity of an object and cause linear translation

• (not muscle contractions) do not act through the center of gravity
• they cause both linear and angular motion

• create angular motion
• couples are forces that
  are equal in size, non-colinear, and act in opposite directions

• HUGE forces
• distance is really small.

• middle
• output forces are modest, input distance is modest

• WEAK output forces
• HUGE distances

• Gravitational
• Strain (or spring) energy

• strongest contraction force is produced at the slowest speed
• max POWER occurs at 1/3 -1/2 of a muscles max contraction velocity

the capacity to do work

the stress that acts perpendicular (or normal) to the analysis plane

A transverse stress that acts parallel to the plane of analysis

• More complicated
• creates different stresses at the analysis
  plane
  • creates both tensile & compressive forces

Bone remodels according to the stresses place upon it

Occur when torques act about the long axis of an object

• Each material has a property (Poisson’s ratio)
• determines the amounts of
  axial strain to transverse strain experienced during loading

The ability to stretch under tensile load but then return to it’s original shape

The ratio of stress-to-strain is called elastic modulus of a material

the ability to absorb stress/shock/assualt and return to a previous state