Unit 5

Question 1

Why do scientists use SI units?

Answer 1

Ensures measurements are consistent and recognised globally
Because of universal standardisation

Question 2

Define what a scalar quantity is

Answer 2

A quantity that only has magnitude

Question 3

Give examples of scalar quantities

Answer 3

Distance, temperature, mass

Question 4

Define what a vector quantity is

Answer 4

A quantity that has magnitude and direction

Question 5

Give examples of vector quantities

Answer 5

Displacement, velocity, force

Question 6

What are Cartesian coordinates?

Answer 6

Points that are relative to a fixed reference point used in the form (x, y, z)

Question 7

What are polar coordinates?

Answer 7

Points that show how far away from the origin it is along and the angle

Question 8

List the stages of the scientific method in order

Answer 8

Observation -> Question -> Hypothesis -> Experiment -> Conclusion -> Result

Question 9

What is a hypothesis?

Answer 9

A tentative explanation for an observation or scientific problem that can be tested

Question 10

What are the characteristics of useful data?

Answer 10

Accuracy, precision, reliability and repeatability

Question 11

Define accuracy in terms of data

Answer 11

How close a set of measurements are to their true value

Question 12

Define precision in terms of data

Answer 12

How close data values are close to each other

Question 13

Define reliability in terms of data

Answer 13

How trustworthy the data is

Question 14

Define repeatability in terms of data

Answer 14

The amount of times you can redo the same test and get the same result

Question 15

Give examples of engineering measurement tools

Answer 15

Engineering rule, vernier caliper, micrometer

Question 16

What does a dial test indicator do?

Answer 16

Checks for runout when holding a billet in a lathe
Checks for flatness of a surface
Calibrates machines

Question 17

Give the difference between a ‘go’ gauge design and a ‘no-go’ gauge design

Answer 17

Go gauge - Must fit, checks maximum metal condition (tightest limit), used to check many dimensions

No-go gauge - Must NOT fit, checks lowest metal condition (loosest limit), used to check only one dimension

Question 18

What is a coordinate measuring machine (CMM)?

Answer 18

Device that measures geometry of physical objects by using discrete points on the surface of the object with a probe

Question 19

What is an atom?

Answer 19

Smallest unit of matter

Question 20

What does an atom consist of?

Answer 20

Nucleus, protons, neutrons and electrons

Question 21

Define valency

Answer 21

Describes how easily an atom can combine with another chemical species

Question 22

What is an ion?

Answer 22

An atom that bears an electrical charge

Question 23

Positively charged ions are called ________.

Answer 23

Cations

Question 24

Negatively charged ions are called ______.

Answer 24

Anions

Question 25

What is a **covalent bond**?

Answer 25

A bond that involves the sharing of electrons between two non-metals

Question 26

What is a **molecule**?

Answer 26

A group of two or more atoms

Question 27

What is an element?

Answer 27

A substance that cannot be broken down into any other substance

Question 28

Define a solution

Answer 28

Homogenous mixture of two or more components, using a solvent and a solute

Question 29

Define solubility

Answer 29

The degree to which a substance dissolves in a solvent to make a solution

Question 30

Define a suspension

Answer 30

Heterogenous mixture where solid particles disperse through a liquid but do not dissolve

Question 31

What is a compound?

Answer 31

Pure substance that is made from one or more elements

Question 32

What is a mixture?

Answer 32

Two or more elements that combine with being chemically bonded

Question 33

Give ways you can separate mixtures

Answer 33

Filtration Crystallisation Distillation

Question 34

State the difference between primary cells and secondary cells

Answer 34

Primary = high power density, chemical reaction irreversible Secondary = low power density, reversible chemical reaction

Question 35

What is **electrolysis?**

Answer 35

Where ionic substances in a compound become **disassociated** when an electric current is passed through it

Question 36

Explain the process of electrolysis

Answer 36

1. Turn on electricity 2. + ions ---> cathode, - ions ---> anode 3. Positive ions gain electrons, negative ions, lose electrons, turning them neutral 4. Atoms form new substances

Question 37

What is **electroplating**?

Answer 37

An electrolytic process where a metal is disassociated from an electrode and deposited over a metallic or non-metallic surface

Question 38

What is the name of the process of deposition of an oxide film on a metal surface during electrolysis?

Answer 38

Anodising

Question 39

Define **galvanic cathodic protection**

Answer 39

Involves protecting a metal surface using a more reactive metal

Question 40

Define an alloy

Answer 40

A mixture of two or more metals

Question 41

What is linear motion?

Answer 41

Movement in a straight line

Question 42

What is rotary motion?

Answer 42

Movement around an axis or pivot

Question 43

What is reciprocating motion?

Answer 43

Movement repeated up and down or back and forth

Question 44

What is oscillating motion?

Answer 44

Movement that involves a curved backwards and forwards movement that swings on an axis or pivot point

Question 45

Define what a **moment** measures

Answer 45

The tendency of a force to rotate a body

Question 46

Define **torque**

Answer 46

A moment that causes rotation around an axis

Question 47

How do you work out the resultant angle in a resultant force?

Answer 47

Tan-1 (Fv/Fh)

Question 48

How do you work out the resultant force?

Answer 48

R=√Fv^2 + Fh^2

Question 49

What is a **coplanar force**?

Answer 49

A force that acts within a two dimensional plane

Question 50

What does concurrent mean in terms of forces?

Answer 50

Where all lines of action pass through the same point, known as the **point of concurrence**

Question 51

What does non-concurrent mean in terms of forces?

Answer 51

Where lines of action don't pass through the same point

Question 52

Define hydrostatic pressure

Answer 52

Pressure exerted by a fluid at equilibrium at any point of time due to force of gravity

Question 53

Give the formula for hydrostatic pressure

Answer 53

P = ρ * g * h

Question 54

What factors do not affect the pressure in a fluid?

Answer 54

Surface area, volume, mass of the liquid

Question 55

Give the formula for hydrostatic thrust

Answer 55

F = Pa A = ρ g A x