# 2015 Notes from the Marking Centre – Engineering Studies

## Introduction

This document has been produced for the teachers and candidates of the Stage 6 Engineering Studies course. It contains comments on candidate responses to the 2015 Higher School Certificate examination, highlighting their strengths in particular parts of the examination and indicating where candidates need to improve.

This document should be read along with:

- the
*Engineering Studies Stage 6 Syllabus* - the 2015 Higher School Certificate Engineering Studies examination
- the marking guidelines
*Advice for HSC students about examinations*- other support documents developed by the Board of Studies, Teaching and Educational Standards NSW to assist in the teaching and learning of Engineering Studies in Stage 6.

### Question 21

Candidates showed strength in these areas:

- outlining features of earlier cars that have been modified in modern cars to provide improved safety (part a)
- outlining the operation of the disc braking system using the labelled diagram provided (part b)
- identifying features of hydraulic systems (part b)
- using various methods to solve the problem (part c).

Candidates need to improve in these areas:

- outlining advantages of hydraulics over mechanical systems (part b)
- not confusing area with diameter when determining pressure using the P= F/A formula (part c).

### Question 22

Candidates showed strength in these areas:

- identifying a diode and outlining its function (part a)
- recognising that semiconductors have influenced the design of telecommunications products (part b)
- projecting from the top and side views towards construction of the required front view (part c)
- identifying a number of components in the assembled front view (part c).

Candidates need to improve in these areas:

- identifying a capacitor and outlining its function (part a)
- applying AS1100 standards to sectioning of individual assembled components and identifying which components should be sectioned (part c)
- applying AS1100 standards to represent bolts, hexagonal nuts, washers and screw threads (part c).

### Question 23

Candidates showed strength in these areas:

- demonstrating some understanding of engineering properties (part a i)
- identifying features of a suitable manufacturing process (part a ii)
- outlining features of fixed and mobile telephone systems (part b)
- outlining how an analogue signal is sampled (part c).

Candidates need to improve in these areas:

- using correct engineering property terminology (part a i)
- contrasting key features of fixed and mobile telephone systems (part b)
- understanding the process of analogue to digital conversion (part c).

### Question 24

Candidates showed strength in these areas:

- demonstrating an understanding of corrosion protection methods (part a i)
- displaying familiarity with the concept of a sacrificial anode in the context of corrosion (part a i)
- summing moments to calculate the roller support reaction of the truss (part b i)
- using Pythagoras’ theorem to combine horizontal and vertical components into a single force (part b ii)
- identifying an appropriate section plane and the nature of an internal force in a truss member (part b iii).

Candidates need to improve in these areas:

- selecting corrosion protection methods appropriate to the question’s context (part a i)
- identifying the constituent phases of a hypoeutectoid steel and understanding microstructure sketching conventions (part a ii)
- recognising the effect of cold rolling on the grain structure of steel (part a ii)
- recognising that all components in a moment equation must include a force and a perpendicular distance (part b i)
- calculating the resultant angle when resolving mutually perpendicular components into a single force (part a ii)
- selecting an appropriate point about which to take moments for calculating the force in a truss member (part b iii).

### Question 25

Candidates showed strength in these areas:

- identifying and justifying two relevant aircraft propulsion systems (part a)
- understanding control adjustments that can vary the lift force during flight (part b)
- outlining the advantages of ultrasonic testing for use in testing aircraft components (part d).

Candidates need to improve in these areas:

- using technical language (parts b and d)
- correctly identifying and calculating lift and drag forces to determine a lift to drag ratio (part c)
- outlining the process of ultrasonic testing for use in testing aircraft components (part d).

### Question 26

Candidates showed strength in these areas:

- selecting an appropriate method to solve at least one component to balance the tensile force (part a ii)
- selecting an appropriate method to solve the problem (part a iii)
- identifying at least one key point and stating its significance (part b i)
- choosing the correct method to solve the problem (part b ii).

Candidates need to improve in these areas:

- correctly labelling the forces, especially the normal reaction (part a i)
- calculating the correct components of the weight force, perpendicular and parallel to the inclined plane, rather than vertical and horizontal components (part a ii)
- identifying the correct moment arm or velocity ratio to calculate the effort (part a iii)
- identifying the significance of point X (part b i)
- choosing a point inside the elastic range to calculate Young’s Modulus and using compatible units for stress calculation (part b ii).

### Question 27

Candidates showed strength in these areas:

- outlining the general responsibilities of a civil engineer, an environmental engineer and an electrical engineer in the area of design
- providing at least one specific responsibility for at least two of the engineers in the design or construction of the bridge.

Candidates need to improve in these areas:

- understanding the specific roles of the environmental engineer and the electrical engineer in the design and construction of the bridge
- differentiating the roles of engineers between the design phase and the construction phase
- addressing both the design and construction aspects of the project
- assigning relevant tasks to each of the engineers.