6 - Biomechanics

Question 1

def: the application of mechanical laws to living structures, specifically to the locomotor system of the human body

Answer 1

biomechanics

Question 2

what are 4 applications of biomechanical analyses?

Answer 2

• improvement of sports skill techniques
• design of sports equipment
• prevention of injuries
• clinical analysis of movement pathologies

Question 3

def: a non numerical description of a movement based on direct observation, conducted primarily by teachers and coaches

Answer 3

qualitative movement analysis

Question 4

def: a movement is analyzed numerically based on measurements from data collected during the performance of the movement, usually conducted by reasearchers

Answer 4

quantitative movement analysis

Question 5

def: pressing or squeezing force directly axially through body

Answer 5

compression

Question 6

def: pulling or stretching force directly axially through a body

Answer 6

tension

Question 7

def: force directed parallel to a surface

Answer 7

shear

Question 8

def: a rigid bar that turns about an axis

Answer 8

lever

Question 9

what do the bones represent in levers in the body?

Answer 9

the bars

Question 10

what do the joints represent in levers in the body?

Answer 10

the fulcrum

Question 11

def: the exact point where effort is applied(muscle insertion)

Answer 11

the force point

Question 12

def: the exact point on which the resistance acts (segment plus external weight)

Answer 12

resistance point

Question 13

def: the axis of motion

Answer 13

fulcrum

Question 14

def: has its fulcrum at some location between the force point and the resistance point

Answer 14

a first class lever

Question 15

def: has its resistance point at some location between the force point and the fulcrum

Answer 15

second class lever

Question 16

def: has its force point at some location between the resistance point and the fulcrum

Answer 16

third class lever

Question 17

what is an example of a second class lever

Answer 17

wheel barrow

Question 18

what is an example of a third class lever?

Answer 18

elbow

Question 19

what is an example of a first class lever?

Answer 19

seesaw

Question 20

def: the ratio of force arm length to resistance arm length

Answer 20

mechanical advantage of a lever

Question 21

def: the force arm of a lever is longer than its resistance arm, the mechanical advantage favors application of force at the sacrifice of speed

Answer 21

force lever

Question 22

def: when the resistance arm is longer than the force arm, the lever favors the speed and range of motion at the sacrifice of force

Answer 22

speed lever

Question 23

second class levers have a MA of…

Answer 23

> 1

Question 24

third class levers have a MA of…

Answer 24

< 1

Question 25

first class levers have a MA of…

Answer 25

1, < 1, > 1

Question 26

def: the perpendicular distance between the force’s line of action and the axis of rotation

Answer 26

moment arm

Question 27

def: the product of force and the perpendicular distance from the force’s line of action to the axis of rotation

Answer 27

torque

Question 28

def: an imaginary point in the centre of the body where the weight of the body is balanced

Answer 28

centre of gravity

Question 29

what are the three other definitions of centre of gravity?

Answer 29

1. the point intersection of the three cardinal planes of the body
2. the point of exact center, around which the body may rotate freely in all directions
3. the point around which the weight is equal on all opposite sides

Question 30

the CG is approximately ____ below the _______

Answer 30

6 cm below the bellybetton

Question 31

the exact location of the center of gravity varies from person to person depending _____ __________

Answer 31

body proportions

Question 32

what is CG influenced by?

Answer 32

• changing body position

- limb positions

Question 33

why is it useful to determine CG?

Answer 33

• used to describe the movement of the body through space
• important for stability
• it is an important factor in calculating the amount of work done

Question 34

what are two techniques for locating the center of gravity?

Answer 34

• reaction board method

- segmental method

Question 35

how can stability increased?

Answer 35

• bigger body mass
• increasing the size of the base of support
• vertically positioning the CG as low as possible
• increasing friction between the body and the surface contacted
• horizontally positioning he CG near the edge og the base of support towards the oncoming external force

Question 36

def: law of inertia - a body will maintain a state of rest or constant velocity unless acted on by an external force that changes that state

Answer 36

first law

Question 37

def: law of acceleration- force equals mass X acceleration

Answer 37

second law

Question 38

def: law of reaction - 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

Answer 38

third law

Question 39

def: a mechanical quantity that is important in situations involving collisions

Answer 39

momentum

Question 40

what are the three differences between walking and running?

Answer 40

1. in running there is a period when both feet are off the ground
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 face is a much smaller portion of the total gait than in walking

Question 41

running speed =

Answer 41

stride length X stride rate

Question 42

what is length of stride dependent on?

Answer 42

leg length and power of the stride

Question 43

what is leg speed dependent on?

Answer 43

speed of muscle contraction and neuromuscular coordination in running