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Question 1

Viscosity

Answer 1

the flow of a liquid, how fast a liquid flows

Question 2

Low viscosity

Answer 2

runny

Question 3

High viscosity

Answer 3

sticky, thick

Question 4

Laminar Flow

Answer 4

At low velocities a fluid tends to flow without lateral mixing and adjacent layers slide past one another - liquid is streamlined, no abrupt changes in direction or speed

Question 5

Stoke’s Law relies on

Answer 5

Laminar flow

Question 6

Turbulent flow

Answer 6

different layers of fluid cross over and mix, there is changing speeds and directions and little eddies are formed throughout the path - this occurs when the rate of flow reaches a critical level or an obstacle is in the way

Question 7

Thixotrophy

Answer 7

Normally it doesn’t flow but when a force is exerted on it the viscosity lessens and it flows. When the force is again removed the viscosity increases and it stops flowing again (e.g. margarine)

Question 8

Negative thixotrophy

Answer 8

normally it flows but when a force is exerted on it it hardens

Question 9

How to measure flow rates?

Answer 9

measure mass (mass flow rate) or volume (volume flow rate) collected in a time interval

Question 10

Hard material

Answer 10

a material that is not readily scratched or indented (e.g. diamond)

Question 11

Stiff material

Answer 11

• doesn’t easily change shape when a force is applied - large load causes small deformation
• doesn’t extend much (e.g. steel)

Question 12

Elastic material

Answer 12

• retains original shape when stretched

- when an object returns to its original shape after the load is removed (e.g. rubber)

Question 13

Plastic material

Answer 13

• extends irreversibly

- when an object is deformed and doesn’t return to its original shape after the load is removed

Question 14

Ductile material

Answer 14

-can be drawn into wires (e.g. copper)

Question 15

Malleable material

Answer 15

• can be deformed and moulded into shape with a force

- can be hammered into sheets (e.g. gold)

Question 16

Strong material

Answer 16

• large force is required to make it break

- high breaking stress (e.g. steel)

Question 17

Brittle material

Answer 17

• little force is required to crack and break it

- no plastic deformation (e.g. glass)

Question 18

Tough material

Answer 18

• requires lots of force to break

- high energy density (e.g. mild steel, rubber tyres)

Question 19

Forces on a falling/rising ball bearing through a fluid

Answer 19

Upthrust, Viscous Drag, Weight

Question 20

Viscous drag force

Answer 20

described by the relationship known as Stoke’s law

Question 21

Archimede’s principle

Answer 21

the size of the upthrust on the ball bearing - buoyancy force on an object in a fluid is equal to the mass of the displaced fluid

Question 22

How does temperature affect the viscosity?

Answer 22

the higher the temperature the lower the viscosity

Question 23

Why are small objects used to test viscous drag and viscosity?

Answer 23

because larger objects have a big enough drag that it can’t be ignored unlike the drag on smaller objects

Question 24

Viscous drag

Answer 24

• particles move past each other with different velocities, frictional forces between them can slow the flow
• size of the force depends on the viscosity of the fluid

Question 25

Weak material

Answer 25

-low breaking stress (e.g. polystyrene)

Question 26

Flexible material

Answer 26

-has a low young modulus (e.g. natural rubber)

Question 27

Soft material

Answer 27

-surface is easily scratched (e.g. plastic)

Question 28

Hooke's Law

Answer 28

Force is proportional to the extension

Question 29

Tensile

Answer 29

forces stretch the spring

Question 30

Compressive

Answer 30

forces squash the spring

Question 31

How would you identify a stiff material on a force extension graph?

Answer 31

There would be a straight line - the steeper the line the stiffer the material

Question 32

How would you identify a plastic material on a force extension graph?

Answer 32

The line would curve

Question 33

What regions can be identified on a force extension graph?

Answer 33

- elastic region - elastic limit - limit of proportionality - plastic deformation - break point

Question 34

What is the limit of proportionality on a force extension graph?

Answer 34

the point where the material is still elastic and will return to its original shape but doesn't act normally

Question 35

What is the elastic limit?

Answer 35

where the material turns from elastic to plastic so no longer returns to its original shape

Question 36

What is the break point?

Answer 36

the end of the line - the force will cause the material to break

Question 37

Where is the plastic deformation?

Answer 37

where the line begins to curve

Question 38

Stress

Answer 38

force per unit area

Question 39

Strain

Answer 39

ratio of extension to original length

Question 40

Refraction

Answer 40

as light/ a wave passes through a boundary into a more/less dense material it will change speed causing it to change direction

Question 41

Polarization

Answer 41

light goes in all directions however when a polarizing lens is used it blocks the light in one plane (going in one direction)

Question 42

Polarized glasses

Answer 42

stop light going in one plane, reducing the amount of light going into your eye

Question 43

Magnetic field

Answer 43

a region in which a magnet experiences a force - its direction is that in which the north seeking pole of a needle would point

Question 44

Electric field

Answer 44

a region in which a charged particle experiences a force - its direction is the direction of the force on a positively charged particle

Question 45

Electromagnetic waves

Answer 45

electric and magnetic waves - oscillate at 90° to each other and the direction of travel

Question 46

Which waves can be plane polarized?

Answer 46

only electromagnetic can be plane polarized and are affected by a polarizing filter - not longitudinal

Question 47

Polarizing filters angle

Answer 47

work at 90° to each other