1.3 Flashcards

1
Q

define angular distance

A

angle through which a body has rotated in moving from first position to the second

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2
Q

define angular displacement

A

shortest change in angular position/smallest angle through which a body can rotate to reach the second position from the first

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3
Q

value for angular distance when gymnast does double somersault

A

720*

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4
Q

value for angular displacement when gymnast does double somersault

A

0*

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5
Q

define centre of mass (2)

A

position in body which it is balanced in all directions; point at which the mass of a body is said to be concentrated/said to act

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6
Q

describe how performer applies eccentric force to ball (2)

A

is an off centre force; force applied outside the centre of mass of the ball

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7
Q

effect of an eccentric force on a ball (2)

A

create spin/angular motion/rotation; causes swerve/lift/deviation in flight

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8
Q

define the analogue of newtons first law of motion

A

a body will rotate with constant angular momentum unless acted upon by an external angular force

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9
Q

how a figure skater controls angular velocity while performing multiple spin about longitudinal axis (7)

A

AM=AV x MI; AM generated at start when off centre force applied to skater by the ice; start low AV; during arms/legs brought in to reduce MI; increases AV; at end arms/legs out to increase MI; reduce AV to prevent over rotation

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10
Q

define linear motion

A

movement in a straight line

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11
Q

explain how linear motion is created

A

direct force / force applied through centre of mass

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12
Q

velocity equation

A

velocity = distance / time

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13
Q

acceleration equation

A

acceleration = change in velocity / time

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14
Q

explain the concept of conservation of angular momentum using the angular analogue of newtons first law of motion (7)

A

a body will continue to rotate with constant AM; unless acted upon by eccentric force; AM = MI x AV; once in flight any change in MI will cause a change in AV to conserve AM; eg if diver tucks MI reduced so AV increases (means AM conserved during flight); performer can manipulate body shape to change MI and AV as AM remains constant

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15
Q

define angular motion (2)

A

movement of a body (in a circular path) about an axis of rotation; rotation of a body around an axis

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16
Q

explain how angular motion is generated to produce a somersault (2)

A

force applied outside CoM/axis of rotation; eccentric force

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17
Q

describe linear motion

A

movement of a body in a straight line and all parts move the same distance, in the same direction, in the same time

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18
Q

describe angular motion

A

movement of a body in a circular path about an axis of rotation

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19
Q

identify vertical forces acting on gymnast in a handstand and explain their relationship during the handstand (3)

A

weight and reaction force; W = R; forces are equal in size and opposite in direction/net force = 0/ forces are balanced

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20
Q

define angular velocity (2)

A

rate of change in angular displacement; speed of rotation

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21
Q

units of angular velocity

A

radians per second

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22
Q

why a gymnast in a bridge is more stable than a handstand (5)

A

more points of contact with the floor; larger base of support; lower centre of mass; line of gravity at centre of/falls further within the base of support; line of gravity easier to keep in centre of base of support

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23
Q

describe angular motion (2)

A

movement around an axis; generated by an eccentric force

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24
Q

example of angular motion

A

gymnast swings on or around the bar

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25
Q

use newtons laws of motion to explain how a sprinter can maximise performance during a sprint start (3)

A

1 - sprinter will remain stationary unless an unbalanced force acts on him; 2 - greater net/resultant/forward force on the sprinter the greater the sprinters acceleration; 3- sprinter applies force back and down into floor so ground applies equal up and forward force on sprinter

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26
Q

describe what is meant by inertia of a moving object (6)

A

inertia is resistance of a body to change its state of motion; depends on mass (bigger mass greater inertia); resistance to accelerate; resistance to decelerate/stop; resistance to change direction; larger inertia, greater force required to change its state of motion

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27
Q

define moment of inertia (2)

A

resistance of a body to start or stop rotating; resistance of body to change its state of angular motion

28
Q

explain factors that affect MI of rotating object (5)

A

depends on mass of an object; greater mass = greater MI; depends on distribution of mass from axis of rotation; further away from axis = greater MI; greater MI = greater force required to increase or decrease rate of spin/rotation

29
Q

explain why a runner has a flexed knee during the recovery phase of stride action (4)

A

flexed knee means mass of leg is closer to axis of rotation/mass distribution decreases; so MI lower; less force required to move leg through recovery stage; recovery can be quicker/increase stride rate

30
Q

describe the term friction (3)

A

friction occurs when two surfaces slide over one another; friction acts in opposite direction to motion; friction acts parallel to the two surfaces in contact

31
Q

describe how different factors can change amount of friction generated, eg for each (4)

A

rough surface means more F eg boots, tyres/smooth surface means less F eg skis; greater downforce means more F eg spoilers on F1 cars; greater (normal) reaction force means more F eg games player pressing into ground to change direction; hotter means more F eg tyres, roads, ski slopes

32
Q

explain how performers maximise stability, eg for each (4)

A

lower CoM eg ski jumper bend knees on landing; increase size of base of support/more points of contact eg rugby widen stance in contact situation/gymnastics bridge; increase body mass eg NFL put weight on so harder to knock over; make line of gravity central to base of support EG?; make line of gravity closer to resistance force/point of contact eg rugby player lean forward into tackles

33
Q

describe why a performer might want to minimise stability using egs (6)

A

reduce movement time eg set position in sprint start in 100m; increase speed eg lean forward when running to make line of gravity outside base of support; change direction quickly eg when swerving in rugby; rotate from take off eg leaning forward to jump with spin in somersault; decrease stability of ball in flight by using no spin eg penalty apply force through CoM; increase stretch eg defending in netball line of gravity outside base of support

34
Q

define the term friction

A

The resistance to motion of two moving

objects or surfaces that touch

35
Q

how rugby player can increase stability (5)

A

CoM over base of support; lower CoM by bending knees; increase area of base by widening stance; line of gravity in centre of base of support; line of gravity in centre of base of support forwards/player leans forwards

36
Q

explain how perfomer can move theri CoM outside the body effectively

A

fosbury flop; in flight jumper arches their back; CoM will follow pre determined flight path; CoM may pass under bar while jumper clears bar; can clear greater heights with same effort

37
Q

explain how a performer can increase friction to optimise performance using egs (5)

A

increase roughness contact eg sprinter wears spikes to increase F which helps them run faster; increase roughness ground eg tarmacadam track in athletics; increase normal reaction force eg shot putter high mass to increase normal reaction and F to prevent over rotation; increase downforce eg spoiler on F1 cars increase F to increase speed; increase *C eg F1 warm up lap

38
Q

apply newtons laws of motion to explain how a basketballer would jump to block a shot (4)

A

1 - to leave ground player must exert greater force into ground than their weight/reaction force >weight; 2 - accelerate upwards; greater forces, greater acceleration/higher jump; 3 - player pushes down onto ground and ground applies equal and opposite force upwards onto player

39
Q

describe factors affecting friction during performance (4)

A

rough/smoothness of footwear; rough/smoothness of surface/ground; size of downforce/normal reaction force; temperature of surface

40
Q

explain why some performers would want to maximise friction using egs (4)

A

to accelerate eg sprinter wears spikes to aid grip; to slow down/stop eg skier turns skiis sideways to slow; to change direction eg footballer studs to enable to turn quickly; to impact spin on an object eg slice in shot in table tennis

41
Q

explain the factors that affect stability (6)

A

more stable if CoM lower; more stable with larger area of base of support; increase number points of contact can increase area of base; more stable if greater mass; more stable if line of gravity/CoM nearer the centre of the base of support; distribution of body parts can affect CoM which can affect stability (raise arms raises CoM which reduces stability)

42
Q

which of newtons laws is most applicable to a speed skater achieves constant velocity as they travel round the track

A

first

43
Q

define momentum

A

the quantity of motion (possessed by a moving object) or the impetus gained by a moving object

44
Q

equation for momentum

A

mass x velocity

45
Q

explain what is meant by net force (3)

A

sum of all forces acting on a body; 0 is forces are balanced; positive/negative if unbalanced

46
Q

compare what is meant by ‘balanced forces’ and ‘unbalanced forces’ (3)

A

B v U; two or more opposing forces are equal in size v not equal; no change in motion v change in motion; constant velocity/rest v acceleration/deceleration occurs

47
Q

describe how a performer can increase their acceleration use egs (5)

A

increase speed/force eg sprinter apply greater force to blocks/track; increase friction eg long jumper wear spikes to increase F with ground; reduce mass eg high jumper lose weight prior to competition; improve technique eg runner adjust body position so more force generated in a forward direction; reduce AR eg sprint cyclist adopts streamline shape to minimise AR

48
Q

apply netwons second law to show how a hockey player may maximise the balls acceleration (7)

A

acceleration is proportional to size of force applied; hockey player applies larger force to increase A; size of force dependent on velocity of stick as it hits ball; player attempt to max velocity of stick on hit; size of force dependent on mass of stick; may use heavier stick to increase force; heavier stick will maximise acceleration as long as velocity of stick is not lost (can swing heavy stick as fast as light one)

49
Q

describe the changes in the position of the CoM at take off and during flight that maximise performance in the fosbury slop technique (7)

A

take off: CoM raised by lifting arms/knee; CoM stays inside body; flight: high jumper rotates about CoM; CoM moved outside body by arching back; CoM passes under bar; while high jumper passes over bar; enabling greater height to be achieved

50
Q

explain the term balanced force, using eg (3)

A

two or more forces acting are equal in size and opposite in direction or net force = 0 or no change in motion/constant velocity/stationary; eg rugby scrum

51
Q

explain the term unbalanced force, using eg (3)

A

two or more forces are not equal in size or net force is present or change in motion/deceleration/acceleration; eg tennis serve

52
Q

moment of force equation

A

force x distance from fulcrum

53
Q

advantage of 3rd class lever (2)

A

move load through large range of movement; speed of load faster than speed of effort; generate faster speeds/acceleration

54
Q

units for MI

A

kgm2

55
Q

describe how the force of weight acts on a sporting body (3)

A

downward force; acts from CoM; due to gravity

56
Q

explain factors that can affect AR, use egs (5)

A

decrease front cross sectional area decrease AR eg sprint cyclist tuck head and lift knees; smooth air flow around shape decrease AR eg shape of discus; smooth surface decrease AR eg shave legs, lycra clothes; increase speed increase AR eg high speed of sprinter; air density decrease AR decrease eg javelin travels further at altitude

57
Q

eg of second class lever (2)

A

press up where fulcrum is toes/feet; standing on tip toes to defend a shot in netball

58
Q

why second class lever mechanical advantage (5)

A

effort arm longer than load arm; can move large load with relatively small effort/large loads more efficiently; closer the load is to fulcrum the greater the advantage; greater distance between load and effort, greater advantage; mechanical advantage = effort arm / load arm

59
Q

how elbow can act as fulcrum for two different lever systems (4)

A

1st: eg tricep extensions, tennis serve, throwing, fulcrum in middle, EFL; 3rd: bicep curls, effort in middle, FEL

60
Q

how force plates enhance performance (7)

A

analyse posture; analyse gait/running/walking; improve balance; rehabilitation; measure force/power; prevent injury on landing; prostheses design

61
Q

eg of 2nd class lever (2)

A

calf raise; take off phase of high jump at ankle

62
Q

eg of 3rd class lever (2)

A

bicep curl; knee extension when kicking ball

63
Q

explain relationship between size of vertical forces and their impact on size of resulting vertical jump for a basketballer (4)

A

reaction force > weight means theres an unbalanced force on player; means there is a net upwards force; so upwards acceleration; bigger reaction force, greater net upward force/upwards acceleration/height achieves

64
Q

factors that affect horizontal distance travelled by a projectile (4)

A

height of release; speed of release; angles of release; air resistance/shape/spin of object

65
Q

explain shape of flight path of a shot (3)

A

parabolic; weight is dominant force; AR low as speed is low