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PE-Miss Henderson/Mr Cole > Force+newtons laws > Flashcards

Force+newtons laws Flashcards

1
Q

What is Newton’s first law?

A

Law of Inertia

A body will remain in a state of rest unless acted upon by an external force

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2
Q

What is an example of Newton’s first law?

A

Football at rest on penalty spot until a force is applied from players foot

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3
Q

What is Newton’s second law?

A

Law of Acceleration
The rate of change in momentum of a body is proportional to the size of the force applied-takes place in direction the force acts

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4
Q

What is the formula for Newton’s second law?

A

F = M x A

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5
Q

What is an example of Newton’s second law?

A

Acceleration of netball pass proportional to force from players hands and in the same direction

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6
Q

What is Newton’s third law?

A

Law of Reaction
For every action there is an equal and opposite reaction
Reaction force is equal to size and opposite in direction not action force

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7
Q

What is an example of Newton’s third law?

A

Serve in tennis-player pushes downwards on ground (action) and ground pushes upwards on player (reaction)

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8
Q

Define force

A

Push or pull that tends to alter the state of motion of a body

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9
Q

What are 4 external forces that may act?

A

Vertical:
Weight and Reaction

Horizontal:
Friction and Air Resistance

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10
Q

What is weight?

A

Force acts downwards from centre of mass

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11
Q

What is reaction?

A

Force acts upwards from points of contact with ground-reaction to downwards forces

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12
Q

What is friction?

A

Force opposing the sliding motion of one surface across another

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13
Q

What is air resistance?

A

Force acting against direction of motion-opposing movement of body through air

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14
Q

What is DOM?

A

Direction of motion/movement

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15
Q

What are the factors affecting friction?

A

Characteristics/roughness of surface eg.sole of shoe
Characteristics/roughness of surface eg.playing surface
Weight/normal ground reaction force
Temperature eg.high temp increases friction-rubber and track

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16
Q

How can friction be minimised?

A

Increasing smoothness of surface eg.wax on skis

17
Q

How can friction be maximised?

A

Increasing roughness of either surface
Increasing mass/down force
Increasing temp of some materials

18
Q

What are the factors affecting air resistance?

A

Velocity
Frontal cross sectional area
Streamlining and shape
Surface characteristics (smoothness)

19
Q

How can air resistance be minimised?

A

Reducing frontal cross sectional area
Using streamlined shape
Making surface smooth

20
Q

What is net force?

A

Overall force acting on body when all forces considered

21
Q

What happens with a net force of 0?

A

Balanced forces-no movement

22
Q

What happens with a net force of +1?

A

Body accelerating

23
Q

What happens with a net force of -1?

A

Body is decelerating

24
Q

What happens if reaction = weight?

A

No movement

25
Q

What happens if force > air resistance?

A

Acceleration

26
Q

What happens if force < air resistance?

A

Deceleration

27
Q

Define centre of mass

A

Point at which the body is balanced in all directions and from which weight appears to act

28
Q

Where do weight (W) and reaction (R)originate from?

Free body diagram

A 
W = centre of mass
R = points of contact with ground
29
Q

Where do friction (F) and air resistance (AR) originate from?
(Free body diagram)

A 
F = points of contact with ground 
AR = centre of mass
30
Q

Which direction do W and R act?

Free body diagram

A 
W = vertically downwards 
R = vertically upwards, perpendicular to ground
31
Q

Which direction do F and AR act?

Free body diagram

A 
F = mostly same as DOM
AR = opposite to DOM
32
Q

How long are the W and R lines?

Free body diagram

A

W = proportional to mass
R = equal but opposite to all downwards forces
Net vertical force must be in direction of vertical acceleration
If no vertical acceleration-then W and R must cancel out

33
Q

How long are the F and AR lines?

Free body diagram

A

F = proportional to factors affecting it
AR = proportional to velocity…affecting it
Net horizontal force must be in direction of horizontal acceleration
If no horizontal acceleration-then F and AR must cancel out

34
Q

What affects the position of centre of mass?

A

Shape-if regular is centralised
Density of different parts of body-shifts towards denser parts

(CAN ENTER OR LEAVE THE BODY eg.high jump)

35
Q

Define stability

A

Measure of how easily a body is moved from a position of equilibrium or balance

36
Q

What is the relationship between mass and stability?

A

Line of gravity-same as weight line

Base of support-area enclosed by points of contact with ground

PE-Miss Henderson/Mr Cole (21 decks)

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