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Kine 4800 biomechanics > Ch.13 > Flashcards

Ch.13 Flashcards

1
Q

The angular equivalent of linear force is __, which may be thought of as rotary force.

A

torque

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2
Q

The product of a force and the perpendicular distance from the force’s line of action to the axis of rotation is know as __.

A

torque

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3
Q

What is the torque generated if a force of 12N is applied @ a perpendicular distance of 3m from an axis of rotation?

A
  • 36 Nm
  • multiply force (12N) by perp distance (3m)
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4
Q

What is the shortest perpendicular distance between a force’s line of action and the axis of rotation called?

A
  • force arm
  • lever arm
  • moment arm
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5
Q

For any given muscle, the moment arm is the largest when the angle of pull on the bone it is attached to is closest to __.

A

90 degrees

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6
Q

The rotary effect created by an applied force is known as __, or moment of force.

A

torque

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7
Q

What is the formula for torque?

A

T=Fd⌄m

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8
Q

most human movement involves simultaneous tension development in __ __ __ muscle groups, the latter of which controls the velocity of the movement and enhances the stability of the joint at which the movement is occurring.

A

agonist and antagonist

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9
Q

In order to generate torque of 2.5Nm, what magnitude of force must be applied at a perp distance of .8m from the axis of rotation?

A
  • 3.125 N
  • 2.5Nm x .8m = 3.125N
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10
Q

The point of support, or axis, about which a lever may be made to rotate is known as a ___.

A

fulcrum

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11
Q

What does a force directed through an axis of rotation produce no torque?

A

because the force’s moment arm is 0

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12
Q

Within the human body, the __ for a muscle with respect to a joint center is the perp distance between the muscle’s line of action and the joint center.

A

moment arm

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13
Q

When net muscle torque and joint movement occur in the same direction

A

concentric torque

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14
Q

when net muscle torque occurs in the direction opposite joint motion

A

eccentric torque

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15
Q

what acts as a rigid bar?

A

bone

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16
Q

What serves as a fulcrum?

A

joint

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17
Q

What applies force?

A

muscle

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18
Q

Within the human body, the simultaneous action of agonist and antagonist muscle groups on opposite sides of a joint axis is analogous to the functioning of a ___ lever.

A

first-class

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19
Q

A lever positioned with the resistance between the applied load and the fulcrum is known as a ___.

A

second-class lever

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20
Q

a lever positioned with the applied force and the resistance on opposite sides of the axis of rotation is known as a __

A

first-class lever

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21
Q

a lever positioned with the applied force between the fulcrum and the resistance is known as a ___

A

third-class lever

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22
Q

Whenever the resistance arm of a lever is longer than the force arm, the __.

A

resistance may be moved through a relatively large distance

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23
Q

Most muscle-bone lever systems of the human body are the __ class for concentric contractions.

A

third

24
Q

The mechanical effectiveness of a lever for moving a resistance

A

ratio of the moment arm of the force to the moment arm of the resistance

25
Q

Most muscle-bone lever systems in the human body have a mechanical advantage of __

A

less than one

26
Q

T/F: Whenever the moment arm of a force applied on a lever is greater than the moment arm of the resistance, the magnitude of the applied force needed to move a given resistance is more than the magnitude of the resistance.

A

False

27
Q

What is the formula for the mechanical advantage of a lever?

A

moment arm (force)/moment arm (resistance)

28
Q

In the human body, most muscle-bone lever systems are the __

A

third class

29
Q

The angle of maximum mechanical advantage for any muscle is the angle at which the most __ can be produced

A

rotary force

30
Q

The maximum mechanical advantages for the brachialis, biceps, and brachioradialis occur between angles at the elbow of approximately __

A

75 degrees and 90 degrees

31
Q

A state characterized by balanced forces and torques is known as __

A

equilibrium

32
Q

The arrangement of most third-class muscle-bone lever systems in the human body promotes __

A

range of motion and angular speed of the body segments

33
Q

Bodies in motion are considered to be in a state of __ __ with all acting forces resulting in equal and oppositely directed inertial forces

A

dynamic equilibrium

34
Q

What causes a bone to rotate around a joint center

A

rotary component

35
Q

What pulls a bone away from a joint center

A

dislocating component

36
Q

What pulls a bone toward a joint center

A

stabilizing component

37
Q

The angle at the elbow at which maximum flexion torque is produced is approximately __, with torque capability progressively diminishing as the angle at the elbow changes in either direction.

A

80 degrees

38
Q

In the context of Newtons first law of motion, what are the states of a body in equilibrium?

A
  • motionless
  • moving with constant velocity
39
Q

__ refers to the concept indicating a balance between applied forces and inertial forces for a body in motion

A

D’Alembert’s principle

40
Q

balance

A

a person’s ability to control equilibrium

41
Q

base of support

A

area bound by the outermost regions of contact between a body and support surface or surfaces

42
Q

center of mass/mass centroid/center of gravity

A

point around which the mass and weight of a body are balanced, no matter how the body is positioned

43
Q

couple

A

pair of equal, oppositely directed forces that act on opposite sides of an axis of rotation to produce torque

44
Q

dynamic equilibrium (D’Alembert’s principle)

A

concept indicating a balance between applied forces and inertial forces for a body in motion

45
Q

1st class lever

A

lever position with the applied force and the resistance on opposite sides of the axis of rotation

46
Q

fulcrum

A

the point of support, or axis, about which a lever may be made to rotate

47
Q

lever

A

a simple machine consisting of a relatively rigid, bar-like body that may be made to rotate about an axis

48
Q

mechanical advantage

A

ratio of force arm to resistance arm for a given lever

49
Q

moment arm

A

shortest (perpendicular) distance between a force’s line of action and an axis of rotation

50
Q

reaction board

A

specially constructed board for determining the center of gravity location of a body positioned on top of it

51
Q

2nd class lever

A

lever positioned with the resistance between the applied force and the fulcrum

52
Q

segmental method

A

procedure for determining total-body center of mass location based on the masses and center of mass locations of the individual body segments

53
Q

stability

A

resistance of disruption of equilibrium

54
Q

static equilibrium

A

motionless state characterized by
- ΣSFᵥ=0
- ΣSFₕ=0
- ΣSF=0

55
Q

3rd class lever

A

lever positioned with the applied force between the fulcrum and the resistance

56
Q

torque

A

the rotary effect of a force about an axis of rotation, measured as the product of the force and the perpendicular distance between the force’s line of action and the axis

Kine 4800 biomechanics (21 decks)

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