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BPK 142 > 6. Biomechanics > Flashcards

6. Biomechanics Flashcards

1
Q

What is Biomechanics?

A

Biomechanics -
the application of mechanical laws to living structures, specifically to the locomotor system of the human body.

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2
Q

What are some Applications of Biomechanical Analyses? (8)

A

! Improvement of sports skill techniques
! Design of sports equipment
! Prevention of injuries
! Clinical analysis of movement pathologies
! Design of prostheses
! Design of rehabilitation devices
! Animation for film and video games
! Ergonomic redesign in the workplace

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3
Q

What is Qualitative movement analysis?

A

a non-numerical description of a movement based on direct observation.
– Conducted primarily by teachers and coaches.

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4
Q

What is Quantitative movement analysis?

A

a movement is analyzed numerically based on measurements from data collected during the performance of the movement.
– Conducted by researchers.

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5
Q

What is Pressure?

A
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6
Q

What is Compression?
What is Tension?

A

Compression - pressing or squeezing force directly axially through a body

Tension – pulling or stretching force directly axially through a body

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7
Q

What is Shear?

A

Shear – force directed parallel to a surface

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8
Q

What is Mechanical Stress?

A

Mechanical stress = F/A Similar to pressure

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9
Q

What are the LEVERS of the human body?

A

A lever is defined as a rigid bar that turns about an axis.

In the body, the bones represent the bars and the joints are the axes. Contraction of the muscles provides the force to move the levers

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10
Q

What are The three parts of a lever?
(FRA)

A

– The force point (F) —
The exact point where the effort is applied. (muscle insertion)

– The resistance point (R) —
The exact point on which the resistance acts. (segment plus external weight)

– The fulcrum (A) — The axis of motion.

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11
Q

What is the Force Arm? (FA)

A

The force arm (FA) of a lever is the perpendicular distance from the fulcrum to the line of action of the force acting on the force point.

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12
Q

What is the Resistance Arm? (RA)

A

The resistance arm (RA) of a lever is the perpendicular distance from the fulcrum to the line of action of the resistance acting on the resistance point.

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12
Q

What is a First-Class Lever?

A

A first-class lever has its fulcrum at some location between the force point and the resistance point

– A typical example of a first-class lever is a teetertotter or seesaw.

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13
Q

What is a Second-Class Lever?

A

– Second-class levers have their resistance point at some location between the force point and the fulcrum.

– The wheelbarrow is a good example:
– the wheel is the fulcrum
– the weight sitting in the box is the
resistance point
– and the handle is the force point.

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14
Q

What is a Third-Class Lever?

A

– A third-class lever has its force point at some location between the resistance point and the fulcrum.

– most common in the body,
– it permits the muscle to be inserted near the joint and produce distance and speed of movement

– although at a sacrifice of force.

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15
Q

What is THE MECHANICAL ADVANTAGE OF LEVER?

A

The mechanical advantage of a lever –
the ratio of force arm length to resistance arm length
* The efficiency with which a lever is able to magnify forces are described by its mechanical advantage (MA) or mechanical ratio.

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16
Q

What is a Force Lever?

A

Whenever the force arm (FA) of a lever is longer than its resistance arm (RA), the mechanical advantage favours the application of force at the sacrifice of speed, and the lever is called a force lever.

17
Q

What is a Speed Lever?

A

Conversely, when the resistance arm is longer than the force arm, the lever favours speed and range of motion at the sacrifice of force and is called a speed lever

18
Q

Mechanical Advantages of First-Class Levers?

A
19
Q

Mechanical Advantages of Second-Class Levers and Third-Class Levers?

A
20
Q

What is the Moment Arm?

A

Moment arm –
the perpendicular distance between the force’s line of action and the axis of rotation.

21
Q

What is Torque?

A

Torque –
the product of force and the perpendicular distance (moment arm) from the force’s line of action to the axis of rotation. It may be thought of as a rotary force.

22
Q

How to Lift A Heavy Object From the Floor (8)

A
  1. GET HELP, Use techniques that minimize the
    actual weight of the load being handled.
  2. Face the object, feet flat on the floor, at shoulder width, and pointing straight ahead. Ensure that you have a STABLE BASE of support so that you don’t slip as you are lifting the load.
  3. Face the object in the DIRECTION in which you intend to move with it so that you don’t have to turn. Avoid twisting
  4. Keep the object as CLOSE to your body to minimize the reaction torque on the low back
  5. Get a good GRIP
  6. Bend at the knees and hips and keep your BACK as STRAIGHT as possible. Avoid a fully flexed or bent spine.
  7. Lift the object using the KNEE and hip extensor muscles, not by pulling upwards with the arms and back.
  8. Carry the object close to your CENTER OF GRAVITY
23
Q

Tips for Lifting Heavy Box (5)

A
  1. Flat Back > Round Back
    (minimizes ligament strain, L5/S1 disc)
  2. Avoid Full Flexion of the Trunk
    (decreases probability of disc herniation)
  3. Stand for a Brief Period (not walk)
  4. Contract Core Muscles
  5. Avoid Lifting after rising from bed
24
Q

What is the Center of Gravity?

A

The centre of gravity (CG) in human body is an imaginary point in the centre of the body where the weight of the body is balanced.

It may also be defined as:
* The point of intersection of the three cardinal planes of the body—frontal, transverse, and sagittal.
* The point of exact centre, around which the body may rotate, freely in all directions.

25
Q

Where approximately is the center of Gravity in humans?

A

approximately 5 cm anterior to the second sacral vertebra, or 6 cm below the belly button.
On average, it is slightly higher in males than in females –

26
Q

Why Is It Useful to Determine CG? (3)

A
  1. Used to describe the movement of the body through space
  2. Important for stability
  3. It is an important factor in calculating the amount of work done
27
Q

What is the Reaction Board Method?

A

Reaction board method -
used for a static position of the human body.

– Assume that the center of gravity is the fulcrum or balance point and then apply the Principle of Levers

28
Q

What is Balance?

A

Balance is defined as the ability to control equilibrium

29
Q

What is Stability?

A

Stability - firmness of balance

30
Q

Ways to Increase Stability?

A
  • Increasing body mass

– Increasing the size of the base of support in

– Increasing friction between the body and the surface

– Horizontally positioning the CG near the edge of the base of support toward the oncoming external force

– Vertically positioning the CG as low as possible

31
Q

What is Newton’s First Law?
(Law of Inertia)

A

First Law - Law of Inertia

  • “A body will maintain in a state of rest or constant velocity unless acted on by an external force that changes the state.”
  • The amount of inertia a body possesses is directly proportional to its mass

(object at rest will remain at rest)

32
Q

What is Newton’s Second Law?
(Law of Acceleration)

A

Second Law - Law of Acceleration

Force = mass X acceleration
– force in N (newton)
– mass in kg
– acceleration in m/s2

33
Q

How much force must be applied by a golf club to give a stationary 0.10 kg ball an acceleration of 40.0 m/s2?

A
34
Q

What is Newton’s Third Law?
(Law of Reaction)

A

“When one body exerts a force on a second body, the second body exerts a reaction force that is equal in magnitude and opposite in direction on the first body.”

(Every action has an equal and opposite reaction)

35
Q

What is Momentum?

A
  • Quantity of motion that an object possesses
  • Linear Momentum = mass X velocity
  • A mechanical quantity that is important in situations involving collisions.
36
Q

Work Formula

A
37
Q

Power Formula

A
38
Q

A force of 20 N pushes an object 5 m in the direction of the force. How much work is done?

A
39
Q

If you do 100 joules of work in two seconds, how much power is used?

A
40
Q

Difference between running and walking

A
  1. In running there is a period when both feet are off the ground. Consider running as a series of jumps.
  2. In running, there is no period when both feet are in contact with the ground at the same time
  3. In running, the stance phase is a much smaller portion of the total gait cycle than in walking.
41
Q

How to calculate running speed?

A

Running speed = stride length X stride rate

The length of the stride is dependent primarily upon leg length and the power of the stride.

  • Leg speed (frequency) is mostly dependent on the speed of muscle contraction and neuromuscular coordination (skill) in running.

BPK 142 (18 decks)

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