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Biomechanics > Torque > Flashcards

Torque Flashcards

1
Q

Where is the force and load in a class 1 lever? Examples?

A

Both down on either side with fulcrum in the middle
seesaw - atalantoaxial joint

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2
Q

Where is the force and load in a class 2 lever? Examples?

A

fulcrum far left, load down in. middle, force up on right - standing on toes gastroc (wheelbarrow)

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3
Q

Where is the force and load in a class 3 lever? Examples?

A

fulcrum far left, force up in the middle, load down on the right

biceps brachi - elbow joint

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4
Q

what is torque? vetor or scalar?

A

vector the turnin geffect produce by a force

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5
Q

What are the 3 types of external forces,

A

centric, eccentric and force couples

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6
Q

What is a centric force? change in what type of motion?

A

external force directed trhy centre of gravity of an object - change in linear motion as per newtons 2nd law not angular

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7
Q

what is an eccentric force? What type of motion

A

for NOT directed thru centre of gravity - effect of force id change in linear AND angular morions of the object - Newtons 2nd law

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8
Q

What is a force couple? what type pf motion

A

paoir of non-colinear external forces equal but opposite in direction
- angular motion so the object rotates - net resultant foce is 0 so ther eis NO change in linear motion per Newtons first and 2nd law

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9
Q

Ehat is a moment (force or lever) arm defined as?

A

erpendicular (⟂) distance between the lineof action of a force and a parallel line passing through the axis of rotation

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10
Q

What is the torque if a centric force is applied

A

0

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11
Q

to find the moment arm what equation can you use

To find vertical component

A

sinangle = r/x

or fy/F

because

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12
Q

to fully cahracterize a torque one must decscribe what 3 things?

A
  • the size of the torque
    – the axis about which the turning effect is created
    – the direction of the turning effect
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13
Q

How is driection of torque determined?

A

right hand thumb rule

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14
Q

Where is the line of action (pull for a muscle force)

A

Along the line between the tendons

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15
Q

The moment arm of. amsucle changes as the ___ changes

A

joint angle - max AT 90

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16
Q

When muscle force pulls at an angle, only the _____
component of force to the bone
(lever) produces torque; i.e. the ___ component

A

perpendiculat, rotary (vertical)

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17
Q

Wjat does the dislocating/stabilizing compenet do?

A

horizontal. - stablizes or dislococated joint

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18
Q

What are the 3 different types of compenents of muscular torque?

A

Rotary componentn (vertical), stabilizing component (to left), dislocating compenent (to right)

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19
Q

Can an object still have a net force of 0 if it is rotating?

A

yes - net force is only lienar otion

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20
Q

Can an onject be in static equillibirum if it rotating?

A

no external forces and torque must sum to 0

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21
Q

What is centre of gravity?

A

the point in a body around which its mass or weight is balanced and through which the force of gravity acts - where entire mass ot wieght is concentrated

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22
Q

where si CG in human body in anatomical position?

A

right in middle of waist

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23
Q

Cg of human bofy
left to right?
Back to front?
Top to bottom?

A

L to R = midline of bodu
Back to front. = thru shoulder and hips and just forward of ankle joints
Top to botoom - 55% standing height females
57% males
highr in infants and toddlers bc large head and short legs

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24
Q

Cg shifts in direction of ____

A

movement of a body part - depends on weught of body part and distance it moves

25
Q

what is stability

A

the capacity fo an object to return to equillibrium or its original position after being displaced

26
Q

What 3 things is stability affected by

A

height of CG - lower is better
size of base of - larger is better
Weight (heavier is better)

27
Q

can direction of force impact stability?

A

YES

28
Q

CG height is ____ as object si toppled Increase in CG height lead to increase in ___

A

raised, potential energy

29
Q

The ____ the orgiinal ct height the ___ the increase in height

A

lower, greater hence PE is greater an d more work msut be done - lower cg id more stable

30
Q

The most stable position for a person is one that maximizes ____

A

potential engery

31
Q

is CG is ___ base of support the object will return to the original position after displacment which is called ___

A

below, stable equillibrium

32
Q

If the CG is _____ the base of support, stability is only maintained if the line of gravity acting
on CG is _____

A

above, within the base of support

33
Q

What is mechanical work (U) si unit?

A

product of force (F) and displacement (d) in the direction of that force - means by which energy si tranferred from one onject to another

joule (J)

34
Q

to determine amount of work done on an obejct we need to knwo hat 3 things

A

average force of object, direction of force, displacment of obejct while force acts

35
Q

What are three types of msucle contraciton and how does thsi impact work

A

isometric (statitc) = 0 work , concentric (shorterning) = pos, eccentric (lenghneing) = negative work

36
Q

what is mechanical energy defined as?

A

The capacity to dow work also in J

37
Q

what is total mecanical energy?

A

KE + PE

38
Q

What is kinetic energy?

A

objects capacity to do wokr due to the motion of an object

39
Q

What is potential energy?

A

Obejcts capcaity to do work due to position of object

40
Q

Can energy be negative?

A

NO - only positive

41
Q

In a closed system what happens to momentum? Is it same for KE?

A

It is conserved.Not same for KE as during impact some KEis onverted to other forms of energy like heat or sound

42
Q

what are 2 types of PE?

A

gravitational potential energy and strain energy

43
Q

what is gravitation PE?

A

PE due to an objects position relative to earth

44
Q

Is gravity always psoitive in PE?

A

yes

45
Q

What is strain energy?

A

Pe due to the deformation of an object liek pole vaulting - related to stiffness content K and deormation delta x

46
Q

What is the work energy relationship?

A

work done by external forces acting on an object can change th eneergy of that objecy

47
Q

to maximize increase in kinertic energy a ____ force needs to be applied over ____ distance?

A

large force over long distance

48
Q

What is conservation of mechanical energy?

A

In absence fo external forces (other than gracity, no work is done and total mechanical energy is conserved (constant) Ei = Ef

49
Q

What is concervation ofmechanical energy useful in?

A

motion of projectiles
- efore being dropped, an object has PE but no KE
– as it falls, PE decreases because height decreases but
KE increases because it accelerates due to gravity
– the decrease in PE is equal to the increase in KE
– the instant before the object strikes the ground, it has
no PE because height is zer

50
Q

What is power?

A

rate of doing work in watts

51
Q

What is naother definition of (linear) power?

A

product of average force and average
velocity

52
Q

As the velocity of a contraction increases, the
maximal force the muscle can generate ___

A

decreases

53
Q

true or false? the maximal force a muscle can generate is at the max velocity?

A

false?

54
Q

____ msucle strength decreses with age?

A

isometric

55
Q

what is peak effort reffered to? what type of contractipon does it measure

A

reffered to as maximal voluntary contraction (MVC) - isometric

56
Q

How was angular velocity measured in the dorsifelxor experiement.

A

measured “isotonically”
− i.e., a fixed load is moved through a range of motion
as fast as possible
* loads normalized to peak torque duringsometric MV

57
Q

When is max muscle power acheived

A

not at ffastest velocity or largest foce but a compromise between the two - usualy 1/3 of max velocity

58
Q

As the duration of an activity increases, the power output which can be sustained ____
exponentially

A

decrease

Biomechanics (8 decks)

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