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Motion Analysis > Quiz #13 > Flashcards

Quiz #13 Flashcards

1
Q

Lever

A

Fulcrum

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2
Q
  • Effort force, Effort arm
  • Resistive force, Resistive arm
A

lever

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3
Q

Levers:
Classified according to the relative positions of the _, effort force and resistive force

A

fulcrum

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4
Q

MA >1 = _
MA <1 = _

A
  • mechanical advantage
  • mechanical disadvantage
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5
Q
  • Axis between effort force and resistive force
  • May act with or without a mechanical advantage
  • see-saw, elbow extension, head extension
A

1st class lever

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6
Q

cervical flexion/extension

A

1st class lever

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7
Q
  • Resistance in between mechanical advantage
  • Not as versatile as 1st class lever
  • push-up, wheelbarrow
A

2nd class lever

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8
Q

Calf raise

A

2nd class lever

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9
Q
  • effort force in middle
  • mechanical disadvantage
A

3rd class lever

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10
Q

knee extension

A

3rd class lever

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11
Q

Anatomical levers:
muscle usually has a _ _ _ (inserts close to axis)
- this provides an advantage for increasing range of motion and velocity of distal points
- however, it also produces a mechanical disadvantage (MA<1)
- thus, muscle forces generated must be in excess of resistant forces

A

small effort arm

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12
Q

Anatomical levers:
Force of muscles can be resolved into two components:
1. on perpendicular to the attached bone
- this produces _
2. one parallel to the bone
- this produces _

A
  • torque
  • stabilizing or dislocating force
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13
Q

With no external force acting on an object that object wants to:
- not move if it wasn’t moving to begin with
- angular
- object continues rotating at constant speed (assuming the rigid body)
- angular momentum of an object remains constant unless a net external torque is exerted on it
- the principle of conservation of angular momentum

A

Angular Analog Newton’s First Law

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14
Q

Angular momentum:
- rigid object: Ha=Ia(t)a
- no external force causing rotation acts on spoon, therefore (t) remains _
- gravity - acts through the spoon’s center of mass

A

constant

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15
Q

Angular momentum:
- non rigid object: Ha=Ia(t)a
- according to Newton’s first law angular momentum remans constant
- therefore, if I changes (t) will _

A

change

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16
Q

A net external torque causes
- the object to angularly accelerate in the direction of the net external torque
- the object’s angular acceleration to be directly proportional to the net external torque and inversely proportional to its moment of inertia
- Net joint torque - torque necessary to produce the segmental acceleration present

A

Angular Analog Newton’s Second Law

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17
Q

For every action there is an equal and opposite reaction
- for every torque exerted by one body on another body, there is an equal and opposite torque exerted by the latter body on the former

A

Angular Analog Newton’s Third Law

18
Q

Angular Impulse:
- A net angular impulse causes a change in _ _
- while in air long jumper swings legs clockwise the upper body counteracts by rotating counterclockwise
- muscles cause torque on both ends of segment

A

angular momentum

19
Q

Twisting:
While in flight
- although angular momentum remains constant (no net torque); transferring angular velocity from on axis of rotation is possible

A

Body twist technique

20
Q

Twisting:
While in flight
- even when total angular momentum is 0, generating a twist in midair is possible when the body is composed of at least 2 segments

A

Cat twist technique

21
Q

The product of the force applied to a body and the displacement of the object

A

work

22
Q

Work:
U=F*d
- direction of force parallel to line of displacement

A

mechanical perspective

23
Q

Work:
U=Fcos^-1d
- direction of force not parallel to line of displacement
- equal angle between displacement and line of application

A

Physiological perspective

24
Q

To determine the amount of work being done, need to know:

A
  • the average force exerted on the object
  • the direction of this force
  • the displacement of the object along the line of action of the force during the time the force acts on the object
25
Q

Bench press:
_ - lifter burnt calories, thinks he did work based on effort
_ - no work was done on the barbell because it was in the same position when the lift ended as when it started

A
  • physiologically
  • mechanically
26
Q

Work:
done by a force acting on an object if the object is displaced in the same direction as the force
- throwing a ball
- lifting phase of a lift
- jumping off the ground

A

positive work

27
Q

Work:
done by a force acting on an object when the object is displaced in the direction opposite the force acting on it
- catching a ball
- lowering phase of a lift
- landing on ground

A

negative work

28
Q

The capacity to do work

A

energy

29
Q

Mechanical energy:
_ - energy due to motion
_ - energy due to position

A
  • kinetic energy
  • potential energy
30
Q

A moving object has the capacity to do work due to its motion
_ energy is affected by the mass and velocity of the object

A

kinetic

31
Q

Energy an object has due to its position
Two types:
- gravitational
- strain energy

A

potential energy

32
Q

Potential energy due to an object’s position relative to the earth
- object’s weight and its elevation or height above the ground or some reference

A

gravitational potential energy

33
Q

Energy due to the deformation of an object
- _ of an object is related to the object’s stiffness, its material properties and its deformation
- pole vault
- shooting a rubber band

A

strain energy

34
Q

The rate of doing work or how much work is done in a specific amount of time

A

power

35
Q

Average force parallel to displacement times average velocity
- dw/dt
- F x V

A

power

36
Q

Regardless of strategy, work would be the same.
The combination of force and velocity determine _

A

power

37
Q

cycling
- what gear to use: high gear = large force/slow pedal rate, low gear = smaller force/faster pedal rate
Running
- stride length vs stride rate
- long stride = high force/slow stride rate
- short stride = lower force/ higher stride rate

A

Power - sports

38
Q

Power - sports
- How do we make these decisions?
- Recall: _ produce the force for human performance

A

muscles

39
Q

Power:
- as velocity of contraction increases, max force of contraction decreases
- in other words, slow contracting muscle can produce greater force than fast contracting muscle

A

power production characteristics of muscle

40
Q

max muscle power =

A

velocity of contraction x max force of contraction

41
Q

Max power output occurs at a velocity approximately _ the muscle’s max contraction velocity

A

one-half

Motion Analysis (14 decks)

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