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Year 8 Science > 7K - Forces > Flashcards

7K - Forces Flashcards

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1
Q

What is a force?

A

A push or a pull.

Can change the shape of something, its speed and the direction it is moving.

Can be big or small

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2
Q

What is the measurement for forces

A

Newtons

N

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3
Q

What are the types of forces

A

contact

non-contact

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4
Q

What are contact forces?

A

Forces that act between two objects that are physically touching each other.

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5
Q

Give examples of contact forces?

A

friction

air resistance

water resistance (buoyancy)

upthrust

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6
Q

What are non-contact forces?

A

A force that one object can apply to another object without touching it.

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7
Q

Give an example of a non-contact force

A

gravity

static electricity

magnetism

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8
Q

What do arrows show about different forces

A

bigger arrows= bigger forces

smaller arrows= smaller forces;

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9
Q

How do arrows show direction

A

The arrow point from the direction it is coming to the direction it is going

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10
Q

What is weight?

A

The force of gravity pulling on it.

Force= measured in Newtons

Gravity= greater on Earth than Moon

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11
Q

What is mass?

A

This is the amount of matter making up an object.

Measured= g/kg

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12
Q

What is the stretch?

A

to make longer without tearing or breaking.

Amount depends on type of material

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13
Q

What is a springs?

A

A coil of wire

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14
Q

What are springs used in?

A

force metres

  • depending of force spring stretches
  • pointer moves further on the scale
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15
Q

What is an extension

A

Make shorter.

Amount depends on type of material

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16
Q

What is the elastic material?

A

Point beyond which spring becomes permanently stretched therefore the spring will not return to its original length when the force is removed

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17
Q

What is a plastic material?

A

Objects that do not return to its original shape when force is removed.

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18
Q

What happens when a force is removed from an object?

A

returns to original length

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19
Q

What is an elastic material?

A

Something that will stretch then returns to original shape of length.

Something that changes shape when a force is applied/ acts on it and then returns to its original shape.

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20
Q

What does Hooke’s law saw?

A

i newton= 4cm

proportionality

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21
Q

What is Hooke’s law?

A

-When a spring stretches, the extension of the spring is proportional to the force stretching it, provided the elastic limit of the spring is not exceeded.

-the extension of a spring is proportional-proportional up to a certain point- limit of proportionality

-1 newton increased= string stretches same amount

-applies to elastic materials

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22
Q

What is Friction?

A

The force between two objects in contact that opposes the motion of either object.

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23
Q

How can friction be useful?

A

car tire- rubber

sitting on chair

walking

drinking tea

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24
Q

How can friction be bad

A

wear things away

riding a bike

car= produces heat and noise

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25
Q

What is friction due to gases and liquids?

A

slow things down

  • air resistance
  • water resistance

reduced by smooth shapes and surfaces

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26
Q

What is a lubricant?

A

Substances that are added between surfaces to decrease/reduce friction

adding a lubricate= lubrication.

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27
Q

What is an independent variable

A

Variable that is manipulated

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28
Q

What is a dependant variable

A

The variable you measure.

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29
Q

What is a control variable?

A

Helps us collect data in experiments.

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30
Q

What is the formula for pressure?

A

Force (N) / Area (m^2)

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31
Q

What is the unit for pressure?

A

size of

  • force
  • if area unchanged
  • larger force = larger pressure
  • area
  • if force unchanged
  • larger area = larger pressure
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32
Q

What is pressure

A

-Is the amount of force pushing on a contain area.

  • measured in Newtons(N)
  • area in metered squared.
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33
Q

What are the units for pressure?

A

Pascals (Pa)

Newtons/Meters squared

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34
Q

What is atmospheric pressure

A
  • pressure of the air on the Earths surface

-100,000 pascals

  • you do not notice as fluids in your body is at a similar pressure
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35
Q

What is the change in pressure on Earth?

A

Deep under the ocean the pressure is greater due to the water above.

The top of a mountain pressure is low as there is less air above.

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36
Q

How to decrease pressure in a fluid?

A

-take away particles

-cool the fluid

-increase container size

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37
Q

How to increase pressure in a fluid?

A

-add partials

-heat the fluid

-decrease container size

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38
Q

What is the impact of air on fluid pressure?

A

increases because particles move faster, and hit the surface harder

39
Q

What is a balanced force

A

when to forces on an object are the same strength but in opposite directions

40
Q

What is an unbalanced force?

A

when to forces on an object are the different strength but in the same directions

41
Q

What does it mean to be stationary

A

not moving; not changing

42
Q

What does it mean to be at a steady spead

A

To have a constant speed

43
Q

What are the states of matter?

A

solid

liquid

gas

44
Q

What is a solid?

A

-Definite shape and volume

  • cannot flow

-difficult to compress

  • particles
  • spacing close
  • strong forces
  • vibrate in fixed position
45
Q

What is a liquid?

A

-no definite shape

  • a definite volume.

-difficult to compress

  • flows and takes shape of container
  • particles
  • forces fairly strong
  • spacing close
  • move within the liquid
46
Q

What is a gas?

A
  • no definite shape or volume
  • spreads in all directions
  • easy to compress
  • particles
  • weak forces
  • far apart
  • move in fast in all directions
47
Q

What is diffusion?

A

when particles spread and mix with each other without anything moving them.

48
Q

What is a Brownian Motion

A

An erratic movement of small specks of matter caused by being hit by the moving particles that make up liquids or gases.

49
Q

What does it mean to have a contact force?

A

To get smaller.

50
Q

What does it mean to expand?

A

To get bigger.

51
Q

What is density?

A

the amount of mass that one cubic centimetre of a substance has. Often measured in grams per cubic centimetre (g/cm^3) or (kg/m^3)

52
Q

What is the Greek symbol for density?

A

rho (ρ)

53
Q

What is the formula for density?

A

mass/volume

54
Q

What is the mass formula

A

density x volume

55
Q

What is the mass formula?

A

Mass/density

56
Q

What is floating?

A

objects sitting above the fluids

57
Q

What is sinking

A

To move downward below the surface of a liquid.

58
Q

What is the difference between upthrust in air and in water?

A

In water is greater than in air because the density of water is higher than in air.

59
Q

What is the difference between upthrust in air and in water?

A

In water is greater than in air because the density of water is higher than in air.

60
Q

What is the density of water

A

-1g/cm^3

-1g/ml

-1kg/m^3

61
Q

What is evidence

A

Data or information that either supports a statement or shows that it is not true.

62
Q

What does it mean for a substance to expand?

A

To increase in size or amount.

63
Q

What is a particle model?

A

A simplified motion diagram that shows the object in motion as a series of points.

64
Q

What is a particle theory?

A

Is that matter is made up of atoms and that they can be divided.

65
Q

What is volume?

A

The amount of space an object takes up.

66
Q

What is an anomalous?

A

abnormal; irregular

67
Q

What is boiling?

A

When a liquid changes to a gas

68
Q

What is a boiling

A

The temperature at which a liquid changes to a gas.

69
Q

What is a change state?

A

The change of a substance from one physical state to another.

70
Q

What is a chemical change

A

A change in matter that produces one or more new substances

atoms cpmbine in different ways to give new stubstances

e.g.

combustion

neutralisation

71
Q

What does it mean to condense.

A

The change from a gas to a liquid.

72
Q

What does it mean to evapourate?

A

To change from liquid to gas.

73
Q

What does it mean to freeze?

A

To change from liquid to solid

74
Q

What does it mean to melt?

A

To change from solid to liquid.

75
Q

What is a freezing point?

A

The temperature at which a liquid changes into a solid.

76
Q

What does is sublimations?

A

when a solid turns into a gas without being a liquid.

77
Q

What is a melting point?

A

The temperature at which a solid becomes a liquid.

78
Q

What is a physical change?

A

A change on state that does not change a substance.

79
Q

What is water vapour?

A

Water in the gas form (steam).

80
Q

What is a fluid?

A

A substance that flows

A gas or a liquid

81
Q

What is pressure?

A

-The amount of force pushing on a certain area. A way of saying how spread out a force is. Often measured in newtons per square metre (N/m2 ) or pascals (Pa).

  • in liquids and gases the force at which particles hit other things.
82
Q

What is upthrust?

A

-A force that pushes things up in liquids and gases.

  • items float when the upthrust is equal the the weight of the item
  • reason you feel you way less in water
83
Q

How you can know if something floats?

A

compare density of fluid with the density of the object.

84
Q

What is the density of water?

A

1g/cm^3

85
Q

What happens to a substance that is less or more than the substance it is in?

A

the item will float.

the greater it is above this the more submerged it is.

86
Q

What is the density of air

A

0.001 g/cm^3

87
Q

Why hot air balloons float?

A

pressure of the hot air, basket and passengers is less than the air pressure.

88
Q

Why is water different?

A

unlike the solid state of other materials, solid ice does not sink in liquid water.

89
Q

What is weight?

A

The amount of force with which gravity pulls things. It is measured in newtons (N). Your weight would change if you went into space or to another planet.

90
Q

What is air resistance?

A

A force that tries to slow objects down that are moving through air. It is caused by friction and by the objects pushing the air out of the way.

91
Q

What is drag?

A

Another name for air resistance or water resistance.

92
Q

What does it mean to be streamline?

A

Something that is a smooth shape to reduce the air resistance or water resistance.

93
Q

What is water resistance?

A

A force on an object moving through water.

Year 8 Science (7 decks)

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