Biomech Exam 2 Flashcards

1
Q

What does lever arm mean?

A

The distance between the axis of rotation and the point of force application.

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2
Q

What is Torque?

A

The turning effect of a force

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3
Q

True or false? Only perpendicular force can produce torque.

A

True, you can apply force at an angle but it will not be as effective as applying perpendicular force on the rigid body.

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4
Q

True or false? The direction of effective torque will not affect the direction of angular acceleration.

A

False, Angular acceleration will go the same direction as net torque or effective torque.

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5
Q

True or false? In order to be effective a torque has to be applied over time.

A

True

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6
Q

On a torque time curve, what variables can be seen on the chart?

A

Peak Torque = highest magnitude
Increase in Slope = Rate of Torque development
Decrease in Slope = Rate of Torque fatigue
The area under the curve = Angular Impulse

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7
Q

What is the symbol for Angular Impulse

A

Delta H

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8
Q

What is an effective mechanical advantage?

A

Perpendicular Distance A / Perpendicular Distance B
When perpendicular distance A is larger than distance B

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9
Q

If you wanted to apply greater torque would it best to apply it at a farther distance from the axis of rotation? Would this be a mechanical advantage or disadvantage?

A

Yes, to create greater torque applying force farther from the axis of rotation would be more advantageous than applying it closer.

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10
Q

What is an effective mechanical disadvantage?

A

When perpendicular distance A is shorter than perpendicular distance B.

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11
Q

What is energy?

A

The state of matter that makes things change or has the potential to make things change

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12
Q

Mechanical energy has two subdivisions, name both and their related subdivisions too.

A

POTENTIAL ENERGY, gravitational energy, and strain energy

KINETIC ENERGY, Linear, and angular

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13
Q

What is the difference between gravitational and strain potential energy?

A

Gravitational relates to the energy associated with the position, where the higher the object is the more GpE is created.

Strain relates to the energy associated with deformation where the more it is pulled or changes shape the more energy will be made, EX. resistance band

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14
Q

True or false?
Linear and Angular kinetic energy refers to the object in motion and where velocity is more impactful to its generation of energy.

A

True

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15
Q

What is the conservation of energy?

A

Energy cannot be created nor destroyed, it can be moved from one place to another or changed from one form to another.

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16
Q

What is the definition of work?

A

The process by which we either increase or decrease the amount of energy in a system.

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17
Q

What is the formula for work?

A

W = Force x displacement

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18
Q

What is the difference between positive and negative work?

A

Positive work means generating energy or putting more energy into a system. (Positive force times positive displacement / negative force times negative displacement)

Negative work means absorbing energy or taking energy out of a system. (Positive force times negative displacement / Negative force times positive displacement)

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19
Q

True or false?
Energy is a vector.

A

False, energy is a scalar.

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20
Q

What is the equation for work regarding angular kinetics?

A

W = Torque x angular displacement
(Torque and force are the same)

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21
Q

What is the equation for mechanical energy expenditure?

A

MEE = +W + |-W|

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22
Q

What is the equation for efficiency?

A

Efficiency = (Output / input) x 100
or
Efficiency = (Mechanical energy expended / Metabolic energy) x 100

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23
Q

True or false.
Some activities are 100 percent efficient.

A

False, there are no activities that are 100 percent efficient.

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24
Q

Describe where the center of mass will be for walking gait.

A

The center of mass will be at its low point at initial contact and toe-off, whereas the center of mass will be at its high point during midstance.

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25
Q

Describe where the center of mass will be for running gait.

A

The center of mass will be at its high point at initial contact and toe-off whereas the center of mass will, be at its low point during midstance.

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26
Q

What is the definition of power and its linear and angular formula?

A

Power is the time rate of doing work, and how much force you can develop while moving quickly.
P = W/ delta time
P = Force times velocity
P = Torque times angular velocity

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27
Q

What is the difference between a perfectly elastic collision and a perfectly inelastic collision?

A

A perfectly elastic collision will conserve kinetic energy while a perfectly inelastic collision does not conserve kinetic energy.

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28
Q

What is the coefficient of restitution?

A

How bouncy a ball is and in sports the governing body limits the coefficient of restitution.

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29
Q

What is the effective mass?

A

How much mass is involved in the collision.

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30
Q

The work of which force will change both the kinetic and potential energy of a body?

A

Ground reaction force.

31
Q

What is uniaxial loading and the two types of uniaxial loading?

A

Loading that occurs on a single line.
Compression - The object is squeezed together
Tension - The object is being pulled apart.

32
Q

What is bending and what types of bending are there?

A

Applying the load at an angle causes the body to bend.
3-point Bending and 4-point bending. (Depends on points of contact.)

33
Q

What is shear?

A

Forces applied are offset which causes tissues to slide past one another.

34
Q

What is torsion?

A

A twisting load around the longitudinal axis of the body. Which can lead to shear.

35
Q

What is a change of length called?

A

Deformation

36
Q

In a load and deformation curve, what variables can be viewed on the graph?

A

Slope = Stiffness (Resistance to deformation)
The area under the curve = Strain potential energy (how much energy a material can absorb)
Highest point = Ultimate strength (Strength: the amount of load or force that tissue can tolerate)

37
Q

What are the four mechanical properties of a tissue?

A

Strength, stiffness, toughness, and deformation

38
Q

What kind of injury occurs in the elastic region and plastic region of a load-deformation curve?

A

In the elastic region, there will be a first-degree injury where there is pain but no material damage.

In the plastic region, there will be a second-degree injury where there is material damage (Plastic deformation)

39
Q

What are the four material properties of a tissue?

A

Stress = The distribution of force applied over an area. (Force/area)
Strain = (change of dimension/original dimension) x 100

40
Q

In a stress-strain curve what kind of variables can be viewed on the graph?

A

Slope = Elastic Modulus (Change in stress/change in strain)

The area under the curve = Strain energy density (How dense the energy is

Highest point = Ultimate strain

41
Q

What does stress relaxation tell us about viscoelastic materials?

A

If we hold the strain constant of a viscoelastic material over time the stress will decrease.

42
Q

What does creep tell us about viscoelastic materials?

A

If we apply the load constant of a viscoelastic material over time the material will gradually deform more and more after the end of the initial load.

43
Q

What does strain rate dependency tell us about viscoelastic materials?

A

When a viscoelastic material is loaded more quickly it will be stiffer and stronger compared to when loaded more slowly.

44
Q

In a stress-time curve relating to injuries, when the capacity exceeds the demand what does that mean? Also, what does it mean when the demand exceeds the capacity?

A

When capacity exceeds the demand there is a margin of safety.

When demands exceed capacity this will result in an injury, the severity of the injury depends on how much demand there is.

45
Q

In a stress-action curve relating to injuries, when a repeated action is performed what happens to the capacity?

A

Capacity will eventually diminish leading to the continuous action demand to exceed higher than the capacity resulting in an injury.

46
Q

In a stress-time curve relating to injuries, what happens to the capacity when constant stress is applied?

A

Capacity will eventually diminish leading to the constant applied stress’s demand to exceed the capacity resulting in an injury.

47
Q

What is the difference between acute and chronic injuries on a graph?

A

Acute injuries occur when one stress demand exceeds the capacity.

Chronic injuries occur when a stress action is continuous or one stress is applied constantly over time.

48
Q

How do we avoid injuries?

A

Either increase the margin of safety and capacity, or decrease the demand, or the use of safety equipment.

49
Q

What is the fundamental principle of the MTC?

A

It can only pull not push.

50
Q

What four ways can a MTC act as?

A

Motor, brake, spring, and a strut.

51
Q

When the MTC has positive work (Positive force x positive displacement or negative force x negative displacement) and positive power what kind of action does that represent?

A

Concentric Actions

52
Q

Concentric actions generate what and to where?

A

Energy, to the skeletal system.

53
Q

When MTC has negative work and negative power what kind of action does that represent? Where does that energy come from?

A

Eccentric actions, skeletal system.

54
Q

The MTC’s actions of a motor and a brake are related to what?

A

Motor - Concentric
Brake - Eccentric

55
Q

When a MTC has zero work and zero power what kind of action does that represent?

A

Isometric actions - Strut

56
Q

What is the stretch-shortening cycle?

A

An eccentric action followed by a concentric action

57
Q

What are the three factors of the stretch-shortening cycle?

A

Well-timed pre-activation, short rapid eccentric action, amortization phase.

58
Q

When sarcomeres are end to end this is referred to as? What are their properties?

A

Series, cannot add forces but can add length/velocity

59
Q

When sarcomeres are side by side this is referred to as? What are their properties?

A

Parallel, can add forces but cannot add length/velocity

60
Q

What are the differences between Pennate and Parallel muscles?

A

Pennate muscles will have larger PSCA (Physiological cross-sectional area), short fiber lengths, and more range of motion.

Parallel muscles will have a smaller PSCA, larger fiber lengths, and less range of motion.

61
Q

True or false.
Pennate muscles are going to have more sarcomeres in series which means it will have larger ROM and velocity.

A

False, Pennate muscles will have more sarcomeres in parallel which means it can produce more force.

62
Q

True or false.
Parallel muscles will have more sarcomeres in series which means it will have larger ROM and velocity than Pennate.

A

True

63
Q

On a force velocity curve what does it mean to have a value at zero, lengthening, and shortening velocity?

A

Zero velocity (X-axis) means isometric
Lengthening velocity means eccentric
Shortening velocity means concentric

64
Q

What are the three different fiber types?

A

Type I, Type IIa, Type IIx

65
Q

What is a joint angle and what types of joint angles are?

A

An angle made between two segments, anatomical angle or included angle.

66
Q

What is the difference between a joint angle and segment angle?

A

Joint angle is an angle between two segments, whereas segment angle is an angle between a segment and external force.

67
Q

Every muscle will produce a force that will create three things. What are they?

A
  • Perpendicular force will create torque
  • Force will compress or distract
  • Force will cause sheer
68
Q

What does it mean for muscles to be co-functional?

A

Muscles that do the same exact thing through an energy perspective

69
Q

What is static stability?

A

The ability to maintain a position or return back to its position following a perturbation.

70
Q

What is robustness?

A

The magnitude of perturbation that a joint can tolerate.

71
Q

What is performance?

A

How fast it can return back to its position.

72
Q

What is dynamic stability?

A

The ability to return back to its trajectory following a perturbation.

73
Q

How many degrees of freedom do these synovial joints have?

-Gliding
-Hinge
-Pivot
-Condyloid
-Saddle
-Ball and socket

A

-Gliding, 0 DOF
-Hinge, 1 DOF
-Pivot, 1 DOF
-Condyloid, 2 DOF
-Saddle, 2 DOF
-Ball and Socket, 3 DOF