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PE studies UNIT 3/4 > biomechanics > Flashcards

biomechanics Flashcards

1
Q

define moment of inertia

A

is the bodys resistance to change in its state of angular/rotational force

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2
Q

what’s the formula for moment of inertia

A

MOI= radius of rotation x mass

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3
Q

decreaced inertia means…

A

increased angular velocity

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4
Q

if a figure skater has their legs and arms out whilst spining does this have more or less inertia

A

more inertia

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5
Q

flexion creates more or less MOI ?

A

less

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6
Q

draw a graph that describes the conservation of angular momentum including angular velocity and moment of inertia

A

straight line = angular momentum

low then high then low- moment of inertia

high then low then high= angular velocity

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7
Q

define angular momentum

A

is the rotational or angular motion possessed by an object

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8
Q

how do you increase angular momentum

A

startt off with a jump or run up or improve segmental interaction take off

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9
Q

define the different leavers including: axis/fulcrum, effort/for arm, resistance arm, input(effort) force, output (resistance force)

A

fulcrum/ axis- point around which the lever rotates

effort/ force arm- the distance between the fulcrum and the point at which the force is applied

resistance arm- the distance between the fulcrum and the centre of resistance

input force (effort)- force exerted ON the lever

output( resistance force) -force exerted BY the lever

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10
Q

draw a diagram of first class lever and provide an example

A

tricep extention
header

force(down) fulcrum resistance (up)

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11
Q

draw a diagram of a second class lever and provide an example

A

fulcrum resistance force

push up

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12
Q

draw a diagram of a third class lever and provide an example

A

fulcrum force and resistance

bicep curl

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13
Q

list the factors effecting levers

A
  1. length of levers
  2. inertia of the lever
  3. the amount of force
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14
Q

describe factor effecting levers: the length of levers

A

velocity is greatest at the distal end of the lever
- longer lever greater at impact
- club length increased = increased velocity and momnetum at impact provide the athlete can control the longer lever as italso has an increased mass
- childern and begginers hsould start with a smaller length so its easier

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15
Q

describe the factor effecting levers in terms of inertia of the lever

A
  • the longer the leaver the heaveir it is and therefore the more difficult it is to rotate
  • by gripping down the club in striking sports athlete can reduce the rotational inertia and implement therefore making it easier to swing bunting
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16
Q

describe the factor effecting levers in terms of the amount of force

A
  • the amount of force an athlete is able to generate via their muscles determines the length of the lever the athletes should use
  • longer levers are usually heavier, therefore more force is required to move them.
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17
Q

describe newtons 1st law

A

the 1st law states that an object will remain at rest unless acted on by an external force. the object will move in the direction of the force acted upon the object

inertia is a object resistance to change in it current state or position, an objects inertia is proportional to its mass

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18
Q

describe newtons 3rd law

A
  • states for every action there will be an equal and opposite reaction.
  • if an athlete directs their foot towards the grounf then there will be a ground reaction force of equal force magnitude directed back in the direction towards the athletes foot

example: sprinter or swimmer using blocks to push the athlete forwards.
- tumble turn

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19
Q

describe newtons 2nd law

A

that an objects acceleration is direactly proportionsla to the force acting upon it and its indirectly proportional to its mass.

the greater the force applied to the object the greater the acceleration

f=ma

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20
Q

state the formula to increase momentum

A

f=ma to increase momentum we can increase mass or increase in velocity of the object.

  • an object can only have momenttum if its moving
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21
Q

decribe force motion

A

relates to the magnitude of the force and the direction of the force applied.

athlete pushing strinking kicking applying max effort will effectivley maximise the magnitude of the force applied.

direction of the force applied- force in the direction of the target to increase transfer of momentum through the ball/object

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22
Q

what is the force-time relationship

A

where the acceleration of the object is proportional to the force applied and the impulse is the change in momentum.

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23
Q

how do you create a larger impulse

A

increase the range of motion in preparation phase of throwing an object

eg. discus throw and windup to increse impulse

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24
Q

explain how an archer can adust their technique with the bowstring to increase the force time relationship

A

the longer time in contact with the bowstring and the further back the bowting is drawn the greater the impulse applied and the faster and straighter the arrow will go

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25
Q

draw 2 different graphs relating to time force

A

graph one - short period of time short amount of high force

graph 2 longer period of time lower amount of force.

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26
Q

name an explain the biomechanicle principle behind having foam on the sole of running shoes and identify the benefit to a runner

A

biomechanical principle is force time (impulse)
- impulse is a measure of force applied over time the equation is impulse= force x time

foam increases the time the force is applied by the foot

absorbs impact and decreases peak force

the benefits to the runner is that it prevents injury

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27
Q

when stopping a force we…

A

usually increase the time components so we can decrease the peak force

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28
Q

define coefficient of restitution (COR)

A

refers to the elasticity of an object. the COR determines the measure of momentum that is conserved.

if momentum is perfectly conserved the COR is 1 but if the momentum is imperfect /not conserved the its less than 1 and if its no moving its 0

29
Q

what are the 3 factors that effect the COR of an object

A
  1. the material of the surface
  2. velocity of collision, if the velocity of an object is increased then the COR is decreased as its altering the shape of the object once hit the ground due to a large amount of force
  3. temperature of the materials - as temperature increases so does the COR such as squash
30
Q

in relation to the biomechanical principle of force motion explain how the raised lip at the rear end of a swimming block improves perforcance.

A

allows force to be applied by the swimmer in more of the horizontal direction

thus causing a decrease in the swimmers times because the new blocks allow swimmer to increase their starting accleration.

by producing more force in the direction the swimmer needs to go

31
Q

would a beginner tennis player use a ball with a higher COR? why/why not?

A

no, they need a lower COR as the ball has less elasticity meaning that the ball will be less bouncy and can be better controlled and as beginners are needed to have more control on the ball and hit the ball at a slower velocity

32
Q

define torque

A

a force that produced a rotational movement around an axis point (angular motion) from from an eccentric force (rotational “off centre” force)

torque= perpendicular distance x force

33
Q

how is torque increased

A

the increasing application of force generated by the muscular contraction of the athlete

something with a greater radius means less force is required to still get maximal accelleration

and angle

34
Q

define segmental interaction

A
  • is the transfer of energy/ momentum between body parts. it is the way the body interacts to meet demands of the task.
35
Q

what are the 6 characteristics of segmental interaction

A
  1. body parts move in a sequence to produce large amount of force
  2. starts with largest, strongest and slowest then smallest and fastest resulting in a summation of force
  3. the next segment begins to move as the proceeding has reached max velocity
  4. need to be well balanced to aid transfer
  5. follow through to prevent deaccelleration of last segment & safe dissapation of force
  6. all forces are directed towards the target
36
Q

provide an example of segmental interaction

A

baseball pitcher
legs, trunk, arm, shoulder, elbow and wrist the AM transferrred from lrg to sml groups

…. continue to list all 6 characteristics

37
Q

describe co-ordination continuum

A

the sequencing approach to develop motion.

by co-ordinating segments transferring AV at its peak to produce max force.

38
Q

define balance and 4 ways to improve balance

A

the ability to maintain its position

  • widens base of support = standin shoulder width apart
  • increase SA to ground( points of contact) by standing flat footed
  • lower COG by bending knees
  • maintian line of gravity in the middle of base of support e.g. butt out head in middle
39
Q

descibe the range of motion

A

the degreee at which a body segment moves around a joint while in motion

  • by extending arm in preparation phase allows a higher force production
40
Q

what 3 things can cause optimal projection

A
  1. height of release
  2. projection angle
  3. velocity of release
41
Q

describe turbulant flow

A

flow in which the velocity at which any point varies erradically.
- seperates late
- less pressure

42
Q

describe laminar flow

A

a type of fluid flow in which fluid moves smoothly in individual layers or streams
- seperates early
- more pressure

43
Q

what is form (pressure) drag

A

is the resistance created by the pressure differential between the front and the back of an object moving a fluid (air/water)
- reducing cross sectional area decreases form drag when being in aerodynamic position

44
Q

why is a cyclist helmet tapered towards the back

A

to delay the seperation of the air particles traveling over the helmet

45
Q

what is the boundary separation layer

A

the point at which the boundary layer of fluid passing over the body/onject separaes from the surfaceis known as the boundary layer separation point.

  • for examples golf balls have dimples because they delay the boundary layer separation point
46
Q

define surface drag (skin friction) and how it can be decreased

A

is the friction between the fluid (air/water) and the surface of a moving object

smooth, tightly fitting material will decrease drag such as swimming caps

47
Q

define wave drag and how it can be reduced

A
  1. the resitance formed by the creation of waves at the point where air and water interact
  2. this drag comes from the creation of waves as an object (swimmer/boat) moves through water.

improving buoyancing (eg wearing wetsuit)
making the body /obect more streamlined and improving technique of the swimmer

48
Q

what are the different types of drag

A

form drag
surface drag
wave drag

49
Q

define bernoullis principle

A

the velocity of the fluid flow determines tge pressure systme
- pressure on one side of an object is inversly proportional to the velocity on the same side of the object.
- As the velocity of the fluid increases the pressure decreases.

50
Q

explain how bernoullis principle assists in keeping the frisbee in the air longer and thus enhancing the distance it travels. drw and labell a diagram to assist your explaination (5mark)

A

draw diagram with low pressure on top high on bottom adds direction drag, lift and eccentric force

benuellis principle states the velocity of the fluid flow determines the pressure system. high pressure systme move to low pressure systems causing a lift force on the frisbee

  • the shape of the frisbee allows LV HP to be created underneath and HV LP above the frisbee
51
Q

list some things that effect torque

A
  • angle
  • moment arm
  • force
52
Q

define the magnus effect

A

the pressure differential, high on one side and low on the other, creates a lift force (the magnus force) that causes the ball to move in the direction of the pressure differntial (from high to low)
- magnus force changes the flight path of the ball due to spin while moving through the air.

53
Q

describe why a second class lever system has a high mechanical advantage

A

the force arm is longer then the resistance arm which allows a heavy load to be lifted more efficiently/ less force required to move the load

54
Q

At the commencement of the downswing, the player flexes his elbows and brings the club closer to his axis of rotation. Why does he do this and which biomechanical principle does it relate to?

A

Moment of inertia/angular inertia (1 mark)

When the mass is closer to the axis of rotation, its easier to manipulate (1 mark) and therefore he does this to increase the angular velocity at the commencement of the swing (1 mark)

55
Q

The spin technique is very difficult to master as it involves many biomechanical principles. Identify two biomechanical principles used in the spin that would impact the throwing of the discus.

A

Impulse (force-time) (1 mark)
By completing the spin, the athlete has a longer time to produce a force on the disc (1 mark)
With more time producing a force, more force will be transferred to the disc after the spin. Greater end force equals longer distance (1 mark)

Force motion (1 mark)
By spinning, the athlete generates a greater velocity through the increased acceleration of body parts (1 mark)
This increased acceleration will produce a greater force according to Newton’s 2nd law. Greater end force equals longer distance (1 mark)

56
Q

in relation to a tackle what newtons law affects it the most

A

newtons 2nd law
the greater the bodys momentum the more force that needs to be applied to either stop or slow the player down.

  • as a result when two bodies collide, the one with the most momentum will be less affected.
57
Q

how can a tackler increase impulse

A

by increasing force applied by:
- increasing velocity of the incoming tackler
- increase strengths/mass by going to the gym
- incorporate segmental interaction to produce greater force

58
Q

give an application of moment of inertia in regards to swimming

A

higher elbow brings the mass closer to the axis of rotation/reducing radius of rotation thus decreasing moment of inertia.

  • chealsea can swim with less effort (more efficiently) required to rotate her arm or recovering her arm at a higher velocity
59
Q

in relation to force time how doeas sarah throw a ball faster

A

by producing a greater impulse
- having greater ROM
- principles of segmental interaction
- later release point
- greater follow through

60
Q

how does a soccer player create topspin

A

by applyinf an eccentric force above the centre of the ball.

on the topside of the ball the boundary lyer of air will be colliding with the oncoming air creating a highpressure (low velocity) area of the ball

on the bottom side of the ball the boundary layer will be moving in the same direction as the air passinf by so ther is no collision creating low pressure (high velocity)

pressure differential causes the ball to move from an area of high p to low p cthus creates a lift force called the magnus effect

61
Q

characteristics of topspin and back spin

A

topspin- causes ball to dip/drop quickly traveling less distance. bounce off at a lower angle

back spinon a ball causes it to ris ehigher in the air and travel further.

62
Q

if a golfer swings with the sam eforce and technique in relation to the clubs of 10, 20, 30 and 40 degree clubs which angle will have the greatests distance

A

10 greatest distance ad 40 less didtance due to trajectory.

63
Q

why does a dimpled golf ball travel further than a smooth golf ball

A

a dimpled golf ball has a smaller area of turbulant air behind it, thus decreasing drag. there is also a later boundary separation

64
Q

what are the different levers for a person standing on their tip toes and elbow flexion to do a bicep curl

A

plantar flexion = second class
bicep= third class

65
Q

a drop shot played in tennis would be best executed by placing which typ eof spin on the ball?

A

back spin

66
Q

is it true that velocity before is greater than after the bounce

A

yes

67
Q

the event was to change from freestyle skiing (tricks/jumps) to long-distance ski jumping, an event where competitors take off from a ramp 120m above landing height, describe how the athlete’s angle of release would change at the point of take-off? Furthermore, what type of drag would have the most significant impact on the distance achieved by the jumper?

A

Demands of the task have changed from large vertical displacement to large horizontal displacement (1 mark)

Therefore the athlete would take off at a reduced angle to maximise the horizontal component achieved (1 mark)

Profile/form drag (1 mark)

68
Q

Use your understanding of drag and lift to discuss how the angle of attack of a discus (5o, 45o, 85o) affects the distance achieved.

A

If the angle of the discus is too flat (5) to the oncoming resistance, then drag will be minimised (1 mark) however, there will be no lift created, and subsequently, the total distance will be low (1 mark)

If the angle of the discus is too great (85), then lift will be high (1 mark); however, drag will also be high due to the increased cross-sectional area presented to the oncoming air, reducing overall distance (1 mark)

If the angle of the discus is optimal (45), then the right balance between lift being maximised (1 mark) whilst drag is minimised is attained, allowing for maximal distance to be achieved.(1 mark)

69
Q

Compare and contrast the projectile motion requirements for the two skills pictured below.

basketball free throw and soccer kick

A

Velocity of release - soccer maximises the velocity of release (1 mark) vs Basketball free throw - reduced velocity of release due to less distance requirement (1 mark)

The angle of release - soccer 45o, assuming all other factors are held equal to allow for maximum distance (1 mark) vs basketball free-throw - increase the angle of release to increase accuracy and likelihood of ball going in (1 mark)

Height of release - not relevant in soccer goal kick(1 mark) vs basketball want to increase the height of release for improved accuracy (1 mark)

PE studies UNIT 3/4 (13 decks)

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