Newtons laws of motion Flashcards

1
Q

motion

A

movement

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2
Q

force

A

a push or a pull that alters or tends to alter the state of motion if a body

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3
Q

how can a force make a body move - create motion

A
  • force applied from face of a club head on a golf club onto the golf ball
  • golf ball which was stationary is now moving
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4
Q
A
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5
Q

how can forces make a body slow down or stop

A
  • force applied from hand brakes of a bike
  • bike will slow down or stop (due to friction)
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6
Q

how can forces make a body accelerate

A
  • force from feet if runner to starting blocks
  • 100 m sprinter pushes of blocks which causes acceleration
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7
Q

how can forces make a body change direction

A
  • force from hand of a volley baller to a volleyball
  • volleyball moves in the direction opposite to the direction in which the volleyballer applied the force
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8
Q

how can forces change the shape of a body

A
  • force applied from foot to a football when kicking a ball
  • ball changes shape
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9
Q

Newton’s first law of motion is also known as the

A

law of inertia

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10
Q

N1 - law of inertia

A

a body will remain at rest or uniform velocity until acted on by an external force

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11
Q

inertia

A
  • resistance of a body to change its state of motion
  • (reluctance of a body to start/stop moving)
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12
Q

velocity

A

rate of motion in a particular direction

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13
Q

give an example of newton’s first law of motion

A
  • sprinter remains stationary in blocks until force is applied to blocks
  • once in motion the sprinter will move at constant velocity for the rest of the race until the external forces increase or decrease
  • golf ball remains on tee until hit by club
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14
Q

applications - newton’s first law

A
  • at rest net force = 0
  • action force at rest = body mass + gravity
  • inertia is directly proportional to mass
  • positive net force from muscles is required to overcome the inertia
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15
Q

if there’s an increase in fat mass - what happens (N1)

A
  • inertia increases
  • increasing reluctance to move
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16
Q

what happens if there’s an increase in muscle mass (N1)

A

it adds force so increases acceleration

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17
Q

Newtons law of acceleration

A

the acceleration of the body is proportional to the size of the force and take place in the direction in which the force is applied

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18
Q

acceleration

A

the rate of change in velocity /momentum

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19
Q

momentum

A

the quantity of motion is a dressed by a moving body

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20
Q

momentum calculation

A

mass x velocity

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21
Q

what does newton’s second law say that a change in velocity is due to

A

the force

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22
Q

what must the performer produce to generate a greater acceleration

A

a greater muscular force

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23
Q

example - newton’s second law

A
  • greater force applied to starting blocks increased acceleration from blocks
  • notion is forward in the same direction as force was applied
  • momentum can be increased by swinging arms up at the start
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24
Q

applications - newton’s second law

A
  • an increased magnitude of force applied increased acceleration
  • the greater the action / reaction force above the mass + gravity the greater the acceleration
  • reactive force is opposite to the direction of the action force and takes place in the direction in which the force acts
  • acceleration is inversely proportional to mass
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25
Q

newtons law of reaction

A
  • for every action there’s an equal and opposite reaction
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26
Q

action force

A

the force exerted by the performer on another body

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27
Q

action force example

A

backward and downward force exerted by a swimmer on the blocks at the start of a race

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28
Q

reactive force

A

an equal and opposite force to the action force

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29
Q

example reactive force

A

the forward and upward force exerted by the blocks on the swimmer at the start of the race

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30
Q

example newtons 3rd law

A
  • sprint race start
  • performer applies and action force to the blocks and the blocks apply a reaction force back
  • causing a change in momentum
  • muscular action force applied to the ground results jn equal and opposite reactive forces pushing the performer upwards from the ground
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31
Q

action force stationary

A

mass of person and force of gravity applied to the ground

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32
Q
  • a stationary persons weight and gravity force apply an action force to the ground
  • an equal and oppose ive reactive force is exerted by the. ground

these forces are equal - what will happen

A

no motion

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33
Q

for a player to jump of the ground what force needs to be bigger then the weight and gravity force of the player

A

reaction force / to gain upward acceleration

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34
Q

when jumping why doesn’t the ground move

A

it has greater inertia

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35
Q

apply newtons 3 laws to a vertical jump - law 1

A

1- to leave the ground the player must exert a greater action force into the ground than their body weight so the reaction force is greater than weight force

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36
Q

apply newtons 3 laws to vertical jump - law 2

A

the player accelerated upwards - the greater the force applied to the ground the greater the acceleration upwards and the higher the jump

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37
Q

apply newtons 3 laws to a vertical jump - law 3

A

the player applies an action force downwards to the ground and the ground exerts an equal and opposite reaction upwards on the player

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38
Q

2 types of forces

A
  • internal
  • external
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39
Q
A
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40
Q

internal force (action force)

A
  • generated by the sports performer with the contraction of skeletal muscle
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41
Q

internal force example

A

high jumper must contract the gastrocnemius to plantar flex the ankle and rectus femoris to extend the knee to generate the force needed to drive upwards from the ground

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42
Q

external force

A

comes from outside the body and act upon it

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43
Q

types of external forces

A
  • vertical
  • horizontal
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44
Q

vertical forces

A

weight
reaction

45
Q

horizontal forces

A
  • friction
  • air resistance
46
Q

weight

A

the gravitational force/pull that the earth exerts on a body

47
Q

reaction

A

the equal and opposite force exerted by a body in response to the action force placed upon it

48
Q

friction

A

the force that opposed the motion of 2 solid surfaces in contact

49
Q

air resistance

A

the force opposing the motion of a body traveling t though the air

50
Q

weight - measurement

A

newtons - N

51
Q

how does the weight force act on a body

A
  • always present
  • acts vertically downwards from COM
  • acts in any body on the earths surface
  • dependent upon mass of body
  • greater mass = greater weight force pulling body downwards
52
Q

reaction force

A

equal and opposite force exerted by a body in response to the action force placed upon it

53
Q

give an example of an action and reaction force

A
  • leg /foot exerts a force on blocks
  • blocks exerts a force on the leg / foot
54
Q

when is a reaction force always present

A

when 2 bodies are in contact

55
Q

where are reaction forces present

A
  • in all points of contact
56
Q

if a reactive force is larger than weight force what happens

A

body will accelerate upwards

57
Q

when a reactive force is applied will a greater or smaller mass move more

A

smaller mass

58
Q

the greater the difference in mass of the 2 bodies the what in terms of acceleration

A

further the body with the smaller mass will move

59
Q

if reaction force and weight force are equal what happens

A
  • forces are balanced
  • 0 net force
60
Q

which direction is reaction force

A

vertically upwards

61
Q

what type of force is friction

A

horizontal

62
Q

what direction does friction occur in

A
  • opposite to the slipping motion of one solid body over another
63
Q

if friction is larger than air resistance what will happen

A

body will accelerate
positive net force

64
Q

if friction is equal to air resistance what happens

A

body travels with uniform velocity
0 net force

65
Q

what factors affect friction

A
  • surface characteristics of 2 bodies in contact with
  • roughness of ground surface
  • roughness if contact surface
  • temperature
  • reaction force
66
Q

surface characteristics

A
  • to increase friction force
  • one or more surfaces need to be rough
  • e.g athletics
67
Q

example of a rough ground surface

A
  • athletes run on rubberized track
  • increasing friction force
68
Q

example of a rough contact surface

A
  • sprinters jumpers and throwers west spiked shoes
  • maximizes friction force
  • causing greater acceleration
69
Q

temperature - friction

A
  • of 2 surfaces in contact
  • if temperature increases
  • friction force increases
70
Q

example of increasing temperature to increase friction

A
  • F1 drivers
  • do a warm up lap
  • increasing tyre temperature
  • increasing friction force
  • giving more control when cornering at high speed
71
Q

increasing normal reaction force - friction

A

increased friction

72
Q

example of increasing reaction force to increase friction

A
  • having a higher body mass
  • creates an equal and opposite higher reactive force
  • increasing friction force with ground
  • shotputters: prevents them over rotating and falling out of the circle
73
Q

how can a cross country runner increase friction

A
  • increase roughness of ground surface
  • run in a line on rougher ground track
  • increase softness of contact surface by wearing rubber soles in training shoes
74
Q

what does friction act parallel to

A

2 surfaces in contact

75
Q

how does the down force of an object increase friction example

76
Q

smoother the surface between 2 surfaces in contact how is friction affected

A

there is less
increasing acceleration

77
Q

the smaller the surface area between 2 surfaces in contact does what do the friction force

A
  • decreases it
  • more acceleration
78
Q

example of how sprint cyclists are adapted to reduce friction

A
  • race on smooth velodrome track
  • have super thin 9mm track cyclist tyres
  • less sa on ground
  • more acceleration
79
Q

how are ice hockey players adapted to play using friction

A
  • bigger surface area increased friction so they can change direction , same length blade as boot to increase friction to change direction
80
Q

how do speed skaters use friction

A
  • thin blade sa
  • reduces friction
  • allowing increased velocity
  • thinner and longer than boot
81
Q

how is a figure skater use friction to adapt

A
  • blade is thinner and reduced sa
  • so they can glide over ice
  • toe pick allows them to land safely after leaps and jumps as they can stick it into the ground to increase friction
  • gentle curve with toe pick
82
Q

air resistance - key facts

A
  • shown by horizontal side extending against dom
  • acts from com
  • acts in opposite direction to motion of body
  • force opposing motion of a body is traveling through air
  • form of fluid friction
  • measured in newtons
83
Q

factors affecting air resistance

A
  • velocity
  • shape
  • frontal cross sectional area
  • smoothness of surface
  • density of air
  • mass of body
84
Q

how does velocity affect ar

A
  • increasing v increases ar
85
Q

e.g of v on ar

A
  • increased v of track cyclists
  • increased ar opposing their motion
86
Q

how does shape affect ar

A
  • more aerodynamic the shape the lower the ar
87
Q

example of shape affecting ar

A
  • teardrop is streamlined
  • wide at
  • front narrow at back
  • created a smooth flow around helmet
  • e.g spring cyclist
88
Q

how does frontal cross sectional area affect ar

A
  • lower fsca lower ar
89
Q

example of fcsa reducing ar

A
  • low crouch position of salon skiers or cyclists
90
Q

surface smoothness affects ar

A
  • increased smoothness of sa less ar
91
Q

example of smoothness of surface increasing ar

A

lycra suits of swimmers

93
Q

how does air density affect ar

A

more dense
more ar

94
Q

example of density of air affecting ar

A

-misty or foggy air increases ar
- against motion of golf ball decreasing its distance
- higher altitudes lower ar so golf ball goes further

95
Q

mass of body affecting ar

A

larger mass
larger inertia
lower ar

96
Q

example of mass if body affecting ar

A
  • shot put is heavy
  • lowering ar
  • so it goes further
97
Q

net force

A

overall force acting on a body when all other individual forces have been considered

98
Q

external force

A
  • a force that comes from outside of the body
  • horizontal and vertical forces
99
Q

balanced forces

A
  • when 2 or more forced acting on a body are equal in size but opposite in direction
  • body will be stationary or at uniform velocity
  • net force is 0
  • no change in state of motion
100
Q

what direction can balanced forces occur in

A

horizontal
vertical
both

101
Q

what law do balanced forces refer to

A

N1- no change in state of motion as there is no net
force present

102
Q

in an exam q how do we comment on balanced horizontal/vertical forces

A
  • w = r1 + r2
  • w + r are equal in size and opposite in direction
  • net force = 0
  • linked to N1
  • no change in motion
  • forces are balanced
  • will continue at rest or uniform velocity
  • w=r
  • ar = f
103
Q

unbalanced forces

A
  • when the force acting in 1 direction is greater in size than the force acting in the opposite direction
  • unbalanced forces occur in a vertical horizontal or both directions
  • body accelerates or decelerates
  • net force = +ve or -ve
  • N2 - there is a change in state of motion and a net force is present
104
Q

what forces only act on projectiles

A

air resistance
weight

105
Q

what happens to airborne objects

A
  • they always decelerate
  • due to increased ar force
  • happens immediately after the force causing it to move is applied
106
Q

commentary on projectiles and unbalanced forces

A
  • ar is greater than w
  • net force is -ve
  • body will decelerate
107
Q

commentary on unbalanced forces

A
  • +ve or -ve net force
  • change in motion
  • 2 or more forces are unbalanced
  • a body will accelerate or decelerate or …
  • change direction or shape
  • r>w, w>r, ar>f, f>ar
108
Q

rules when drawing a free body diagram

A
  • use point of application
  • show size by arrow length
  • direction must be accurate