Biomechanics

Question 1

Biomechanics definition

Answer 1

the science (or study) of internal and external forces acting on the human body, and the effects produced by these forces

different actions we do to produce force

Question 2

Newton’s Laws of Motion

1st Law

Answer 2

1st Law: a body stays at rest or in motion, unless acted upon by an external force.
Inertia: The resistance an object has to change in it’s state of motion. (highert mass = more inertia)

a heavier football player would have more inertia and therefore harder to be stopped

Question 3

Newton’s Laws of Motion

2nd Law

Answer 3

2nd Law: The change in velocity (acceleration) of an object is directly proportional to the force applied and inversely proportional to the mass of the object (F=ma)
Impulse: I=F∆t, decides how fast the ball is going to accelerate.
Impulse is a term that quantifies the overall effect of a force acting over time.

F=force, m=mass, a=acceleration, I=impulse, ∆t= change in time

Question 4

Newton’s Laws of Motion

3rd Law

Answer 4

3rd Law: For every action(force), there is an equal and opposite reaction (force)

Question 5

Friction

Answer 5

Friction: A force generated when one body moves across the surface of another body, in the opposite direction of the motion

Question 6

momentum

Answer 6

momentum: the quantity of motion a body possesses; a function of the mass and velocity of the body (P = mv) the mass of the player times their velocity
P-momentum
P-before must = P after the collition

Question 7

Types of motion

1-Linear motion

Answer 7

mov’t in a particular direction (a straight line), force acts on object through its centre of mass. Example: spriter accelerating down track

Question 8

Types of motion

Rotaional motion

Answer 8

mov’t about an axis, force does not act on centre of mass, causing rotation.
Example: bending a soccer ball.

Question 9

Lever Systems

what is a lever?

Answer 9

An instrument for performing work
Bones in body act alone or with others as part of a lever system that facilitates movement
all levers involve a force (effort), resistance (load), and a fulcrum (pivot point/axis)
to lift a boulder (resistance), a rock (fulcrum) and as stick is used along with our force

Question 10

Classes of Levers

Class I lever

Answer 10

fulcrum is located b/w the force and resistance (in the middle)
ex: see-saw, neck

Question 11

Classes of Levers

Class II Lever

Answer 11

The resistance is b/w the force and fulcrum
pivot and effort on both ends, load in the middle facing in
ex: standing on tipy toes, one wheel cart

Question 12

Classes of Levers

Class III lever

Answer 12

The force is b/w the fulcrum and the resistance. This is the most common lever in the body
pivot and load at both ends, effort at the middle facing out
ex: flexion at the elbow

Question 13

7 principles of biomechanics

1`

Answer 13

Lower centre of mass = larger base of support, and more stability

Question 14

7 principles of biomechanics

2

Answer 14

To produce max force, use all possible joints in movement

Question 15

7 principles of biomechanics

3

Answer 15

to produce max velocity, use all joints in order from largest to smallest

Question 16

7 principles of biomechanics

4

Answer 16

the greater the applied impulse, the greater the increase in velocity

Question 17

7 principles of biomechanics

5

Answer 17

movement occurs in direction opposite that of the applied force

Question 18

7 principles of biomechanics

6

Answer 18

Angular motion occurs when force is applied away from axis

Question 19

7 principles of biomechanics

7

Answer 19

Angular momentum is constant when an athlete or object is free in the air

Question 20

stability

When athletes want to become stable, they should:

Answer 20

1. lower their centre of gravity (bend knee)
2. widen their base of support (spread legs
3. Place their centre of gravity in the middle of the base
4. Increase their mass, when possible (wear weight)

Question 21

stability

When athletes want to move quickly (become less stable), they should:

Answer 21

1. Raise their entire entre of gravity
2. narrow their base of support (hug body when want to increase spinning speed)
3. move their centre of gravity outside the base (point your head out when get ready to race)
4. decrease their mass (when possible)

Question 22

maximum effort

when athletes want to exert maximum force they should:

Answer 22

1. use as many joints as possible
2. use joints simultaneosly (at the same time)

ex. wrestling

Question 23

maximum velosity

when athletes want to produce maximum velocity, they should:

Answer 23

1. use as many joints as possible
2. use joints in sequence, beginning with those associated with largemuscle mass
   ex. pitching

Question 24

linear motion

when athletes want to move in one direction, they should:

Answer 24

apply a force in the opposite direction

ex. racing

Question 25

angular motion

when athletes want to spin faster, they should

Answer 25

movement of inertia: relative difference in how easy or difficult it will be to set any object in motion about a defined axis of rotation
when athletes want to spin faster, the should: decrease their movement of inertia

ex. figure skating

Question 26

angular motion

when athletes want to spin slower

Answer 26

increase their moment of incertia
* the further the mass is from the rotation point, the greater the moment of inertia.

Question 27

uses of biomechanics

Answer 27

• analyze and enhance performance
• injury prevention and rehabitation
• fitness and personal training

Question 28

analysis of gait (walking)

phases of normal gait:

Answer 28

the gait cycle is the time interval between the exact same repetitive events of walking.
the defined cycle can start at any movement, but it is generally begun when one foot contacts the ground.

Question 29

two phases of the gait cycle

Answer 29

stance phase: the part of the cycle when the foot is in contact with the ground (60% of cycle)
Swing phase: occurs when the foot is in the air (40% of cycle)

Question 30

the cycle of walking can be divided into 6 further phases:

Answer 30

1. heel strike (HS)
2. Foot flat (FF)
3. Mid-stace (MS)
4. Heel off (HO) terminal stance
5. Toe off (TO) preswing
6. initial & Mid-swing
7. Terminal swing

periods 1-3 make up the stance phase, while periods 4-6 make up the swing phase

Question 31

non-pathological gait patterns in a child

Answer 31

• wider BOS (base of support)
• faster cadence
• shorter stride length
• initial contact with floor is flat foot
• knees remain mostly extended during stance phase

Question 32

non-pathological gait patterns in elderly

Answer 32

• walk slower
• spend more time in stance phase
• longer periods of double support
• shorter steps
• less vertical displacement
• wider BOS
• greater horizontal displacement

Question 33

why study gait?

Answer 33

• to see if developmental milestones are achieved or delayed.
• the ability to walk safely often determines when a patient can be discharged home
• issues involving pain in other areas of body (back, knee, hip, etc.) can originate from improper gait

Question 34

non support

Answer 34

occurs when neither foot is in contact with the floor
does not occur during walking
running- biggest difference between runing and walking is non-support, in speed walking, there is always contact with floor.