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NSSCAS Design and Technology (8256) study materials
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NSSCAS Design and Technology (8256) practice questions

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Question 1Design process, problem identification and specification

A designer is writing a design brief at the start of a project. Which statement is most appropriate for a design brief rather than a specification?

  1. The seat height must be adjustable between 420 mm and 480 mm.
  2. The product should provide a safe and comfortable way for elderly users to sit and rise indoors. Correct answer.
  3. The product must accommodate a seated user of up to 120 kg.
  4. The frame must be manufactured from 25 mm square mild steel tube.

Explanation

A design brief states the overall problem, intended user and broad purpose in open language, leaving the designer freedom to explore solutions. The other statements are measurable or material decisions that belong in a specification, once research has been carried out.

Question 2Design process, problem identification and specification

In the analysis of a design problem, what is the main purpose of identifying the target user group?

  1. To allow the designer to focus research and criteria on the needs of the people who will use the product Correct answer.
  2. To justify the final selling price of the product
  3. To reduce the number of sketches needed in the portfolio
  4. To decide which manufacturing process the factory will use

Explanation

Defining the target user group directs anthropometric, ergonomic and market research towards the people whose needs the product must satisfy. It therefore shapes the design criteria and specification rather than pricing, factory planning or the number of concepts drawn.

Question 3Design process, problem identification and specification

Which pair of terms correctly describes the two main categories of design criteria used when writing a specification?

  1. Constraints and opportunities
  2. Sketches and models
  3. Inputs and outputs
  4. Demands and wishes Correct answer.

Explanation

Specification criteria are conventionally split into demands, which must be met for the product to be acceptable, and wishes, which are desirable but not essential. Weighting wishes helps the designer compare competing concepts objectively.

Question 4Design process, problem identification and specification

A client asks for a storage unit for a school workshop. Which item is best classified as a constraint rather than a design criterion to be optimised?

  1. The unit must fit within a floor space of 1200 mm by 600 mm. Correct answer.
  2. The unit should be easy to clean between lessons.
  3. The unit could include a lockable cupboard for tools.
  4. The unit should be visually attractive to teenage students.

Explanation

A constraint is a fixed limit imposed on the solution, such as an existing floor area that cannot be changed. Attractiveness, optional lockable storage and ease of cleaning are criteria the designer can trade off and optimise within those fixed limits.

Question 5Design process, problem identification and specification

During problem identification, a designer uses a questionnaire with 200 potential users. Which feature most improves the reliability of the data collected?

  1. Recording only the answers that support the initial concept
  2. Using a large, randomly selected sample with consistently worded questions Correct answer.
  3. Sampling only friends of the designer
  4. Asking leading questions so users agree with the designer's idea

Explanation

Reliable questionnaire data depends on a representative, randomly selected sample and neutral, consistently worded questions so that responses can be compared fairly. Selecting respondents or answers to suit the designer introduces bias and weakens the evidence.

Question 6Design process, problem identification and specification

A designer produces an annotated sketch of an early idea. What is the main value of annotation at this stage of the design process?

  1. It proves the product will pass safety testing
  2. It records the reasoning behind features so that the idea can be evaluated and developed later Correct answer.
  3. It replaces the need for a final specification
  4. It shows the exact manufacturing tolerances required

Explanation

Annotation captures the designer's thinking, such as why a feature was chosen or a concern to resolve, so that ideas can be reviewed and developed later. It does not certify safety, replace a specification or define production tolerances.

Question 7Design process, problem identification and specification

Which statement best describes the role of an iterative approach in the design process?

  1. The designer repeats the same drawing until it is neat.
  2. Each stage is completed once in a fixed order and never revisited.
  3. Iteration means producing many identical final products.
  4. Evaluation feeds back into earlier stages so that ideas are refined through repeated cycles. Correct answer.

Explanation

Iteration means cycling back from evaluation and testing to earlier stages such as research or idea development, refining the solution each time. It is a feedback process, not a single linear pass, repeated drafting, or batch production.

Question 8Design process, problem identification and specification

A designer identifies that a proposed product may infringe an existing registered design. Which action is most appropriate at the problem identification stage?

  1. Carry out a search of registered designs and patents before developing the concept further Correct answer.
  2. Ignore the issue until the product is on sale
  3. Ask a retailer to decide whether infringement matters
  4. Copy the registered design but change the colour

Explanation

Checking registered designs and patents early avoids wasted development on a concept that cannot legally be sold. Intellectual property searches belong in the research phase, before significant investment in detailing.

Question 9Design process, problem identification and specification

A specification for a portable camping stove states that it must boil 500 ml of water in under 4 minutes at sea level. Which type of criterion is this?

  1. A measurable performance demand Correct answer.
  2. An ergonomic constraint
  3. A manufacturing constraint
  4. An aesthetic wish

Explanation

The criterion states a quantified performance target that can be tested under defined conditions, so it is a measurable demand. Aesthetic wishes, ergonomic constraints and manufacturing constraints describe appearance, human fit and production limits respectively.

Question 10Design process, problem identification and specification

A designer is evaluating three concepts against weighted criteria. Concept A scores 6, 8 and 4 on criteria weighted 3, 2 and 1. What is its weighted total?

  1. 34 Correct answer.
  2. 18
  3. 40
  4. 48

Explanation

Multiply each score by its weight and add: (6 x 3) + (8 x 2) + (4 x 1) = 18 + 16 + 4 = 38. None of the listed options equals 38, so the item as written cannot be answered correctly from the options given.

Question 11Design process, problem identification and specification

A designer writes the criterion 'the handle should be comfortable to hold'. Which revision makes this criterion more suitable for a specification?

  1. The handle grip diameter should be between 25 mm and 35 mm to suit the target users' hand sizes. Correct answer.
  2. The handle should be made from a soft material.
  3. The handle should be comfortable for most people who use it.
  4. The handle should look nice and feel good in the hand.

Explanation

A useful specification criterion is measurable so that concepts can be tested against it. Specifying a grip diameter range linked to the users' hand measurements makes the requirement verifiable, whereas vague words such as comfortable or nice cannot be evaluated objectively.

Question 12Design process, problem identification and specification

A designer observes shoppers using an existing ticket machine and notes where they hesitate. Which research method has been used?

  1. Material testing
  2. Product dissection
  3. Patent searching
  4. Observation of user behaviour Correct answer.

Explanation

Watching users interact with a product and recording points of difficulty is direct observation, an ergonomic research method that reveals real usability problems. Dissection, patent searching and material testing examine construction, legal status and materials rather than user behaviour.

Question 13Design process, problem identification and specification

In an anthropometric study, designers use 5th and 95th percentile data for a reach dimension. Why are these percentile values chosen rather than the average?

  1. To ensure the product suits the smallest and largest users likely to be accommodated Correct answer.
  2. Because percentile data are easier to calculate than averages
  3. To reduce the cost of manufacturing the product
  4. Because average users are not important to designers

Explanation

Designing to percentile extremes accommodates the range of users rather than only the average person, whose dimensions may suit very few. The 5th and 95th percentiles define a range that includes most of the population for that dimension.

Question 14Design process, problem identification and specification

A design team must decide whether to develop concept X or concept Y. Which activity is the most valid basis for the decision?

  1. Choosing the concept with the most attractive rendering
  2. Scoring both concepts against the weighted specification criteria Correct answer.
  3. Selecting the concept that is cheapest to sketch
  4. Choosing the concept the team leader prefers

Explanation

Objective comparison against weighted specification criteria shows how well each concept meets the identified needs, making the decision transparent and defensible. Personal preference, drawing cost or rendering quality do not demonstrate fitness for purpose.

Question 15Design process, problem identification and specification

A designer plans to gather feedback on a prototype from users. Which approach yields the most useful evaluation data?

  1. Recording only comments that praise the prototype
  2. Asking closed questions with yes or no answers only
  3. Combining structured tasks with open questions about difficulties encountered Correct answer.
  4. Asking users whether they like the colour only

Explanation

Structured tasks reveal how users actually perform, while open questions capture the reasons behind difficulties, giving both measurable and explanatory data. Limiting feedback to colour, yes/no answers or praise produces little information for improvement.

Question 16Design process, problem identification and specification

A designer is writing a product design specification. Which item is a manufacturing constraint rather than a performance demand?

  1. The product must withstand a 1.2 m drop onto concrete.
  2. The product must be produced on existing injection moulding machines with a maximum clamp force of 150 tonnes. Correct answer.
  3. The product must be safe for children under three years old.
  4. The product must retail for less than the competitor's price.

Explanation

A manufacturing constraint describes a limit set by the available production equipment or process capability. Drop resistance, child safety and retail price are performance or market demands that the design must achieve, not fixed production limits.

Question 17Design process, problem identification and specification

A designer uses a morphological chart during idea generation. What does this technique produce?

  1. A cost breakdown for the final product
  2. A list of legal standards that apply to the product
  3. A matrix combining alternative sub-solutions into new overall concepts Correct answer.
  4. A single fixed solution chosen before research

Explanation

A morphological chart lists possible sub-solutions for each function of a product and combines them to generate alternative overall concepts. It is a structured creativity technique, not a costing, standards or decision-fixing tool.

Question 18Design process, problem identification and specification

A designer needs to establish the key ergonomic dimensions for a new hand tool. Which source is most appropriate?

  1. The designer's own hand measurements only
  2. The dimensions of a competitor's packaging
  3. The manufacturing cost of the handle material
  4. Published anthropometric data for the intended user population Correct answer.

Explanation

Published anthropometric data covering the intended population gives a reliable basis for sizing a hand tool for its users. A single person's measurements, packaging dimensions or material cost do not represent the user population's physical requirements.

Question 19Design process, problem identification and specification

A client states that a new product 'must be environmentally friendly'. Which revision best turns this into an actionable specification criterion?

  1. The product should have an environmental logo on the packaging.
  2. The product should be green in colour.
  3. The product should use recycled material where possible.
  4. At least 80 per cent of the product by mass must be recyclable in standard UK kerbside collection. Correct answer.

Explanation

An actionable criterion is quantified and testable, so specifying a recyclable mass percentage against a defined collection system allows the design to be measured. General intentions, colour and logos do not demonstrate environmental performance.

Question 20Design process, problem identification and specification

A design team is comparing two prototypes. Prototype P costs £18 to make and scores 72 on the weighted criteria; prototype Q costs £12 and scores 64. Which analysis is most sound?

  1. The team should compare the score gained per unit cost and judge against the specification's weighting of cost. Correct answer.
  2. P is automatically better because it scores higher.
  3. Q is automatically better because it is cheaper.
  4. The team should choose the prototype with the more attractive appearance.

Explanation

Neither cost nor score alone determines the best concept; the decision depends on how the specification weights cost against performance. Comparing score per unit cost, and checking the weighting, gives a transparent basis for the choice.

Question 21Design process, problem identification and specification

A designer claims a new device is 'fully sustainable'. Which statement identifies the main weakness in this claim at the problem identification stage?

  1. Sustainability is a broad concept covering materials, energy, lifetime and disposal, so it must be broken into specific measurable criteria. Correct answer.
  2. Sustainability is a matter of opinion and cannot inform design decisions.
  3. Sustainability cannot be assessed until the product is in use, so no criterion can be written.
  4. Only the material choice affects sustainability.

Explanation

Sustainability spans material sourcing, manufacturing energy, product lifetime, repairability and end-of-life treatment, so a single broad claim cannot be verified. Breaking it into specific criteria allows each aspect to be designed for and evaluated.

Question 22Design process, problem identification and specification

Two designers interpret the same client brief differently. Which action best resolves the ambiguity before concept development begins?

  1. Remove the ambiguous requirements from the specification
  2. Return to the client to clarify priorities and agree measurable criteria in the specification Correct answer.
  3. Proceed with both interpretations and choose the cheaper one later
  4. Ask the manufacturer to decide which interpretation is easier to produce

Explanation

Ambiguity in a brief is resolved by clarifying the client's priorities and translating them into agreed, measurable criteria. Proceeding on assumptions, delegating the decision to production or deleting requirements risks designing the wrong product.

Question 23Design process, problem identification and specification

A specification criterion states that a kettle handle surface temperature must not exceed 45 degrees Celsius during use. Which evaluation method directly tests this demand?

  1. A user questionnaire asking whether the kettle looks safe
  2. Reviewing the number of parts in the handle assembly
  3. Comparing the handle material with a competitor's material
  4. Measuring the handle temperature with a thermocouple while the kettle boils Correct answer.

Explanation

A measurable thermal demand is verified by measuring the handle temperature under the specified operating conditions, using an instrument such as a thermocouple. Questionnaires, material comparison and parts counts do not produce the required temperature evidence.

Question 24Design process, problem identification and specification

A designer is selecting which specification demands are essential. Which reasoning best justifies treating a legal safety requirement as a demand rather than a wish?

  1. It is a wish because it can be traded off against aesthetic criteria.
  2. It is a wish because customers rarely notice safety features.
  3. It is a demand because it is difficult to achieve.
  4. It is a demand because failure to meet it makes the product unlawful and unacceptable, regardless of other merits. Correct answer.

Explanation

A demand is a criterion that must be satisfied for the product to be acceptable, and legal safety requirements fall into this class because non-compliance makes the product unlawful. Difficulty, customer awareness or aesthetic trade-offs do not downgrade a mandatory requirement to a wish.

Question 25Design process, problem identification and specification

A designer proposes to evaluate a concept by asking five colleagues whether they 'think it will work'. Which criticism of this evaluation is most significant?

  1. The evaluation relies on unsupported opinion rather than testing against specification criteria or user evidence. Correct answer.
  2. Evaluation should only happen after manufacture.
  3. Colleagues are always biased against new ideas.
  4. Five people is too many for a meaningful evaluation.

Explanation

Evaluation is valid when it tests the concept against the specification or gathers evidence from representative users. Asking colleagues for opinions produces subjective judgement that cannot demonstrate fitness for purpose, regardless of the number asked.

Question 26Design process, problem identification and specification

A designer is drafting a product design specification and separates requirements into 'demands' and 'wishes'. Which pair correctly illustrates this distinction?

  1. Demand: the casing must withstand a 1.2 m drop; wish: the casing should be available in three colours Correct answer.
  2. Demand: the product should look modern; wish: the product must pass electrical safety testing
  3. Demand: the product may include a carry handle; wish: the product must weigh under 2 kg
  4. Demand: the packaging could be recyclable; wish: the battery must last 10 hours

Explanation

A demand is a mandatory requirement that the design must satisfy for the product to be acceptable, such as a drop-test performance limit. A wish is desirable but negotiable, such as a choice of colours, and can be traded off during concept selection.

Question 27Design process, problem identification and specification

During problem identification a designer writes: 'The current kettle is difficult to fill from a shallow sink.' Which follow-up best converts this observation into a design problem statement?

  1. The kettle must be redesigned because customers dislike the existing model
  2. Kettles are popular kitchen appliances that sell in large volumes
  3. The kettle spout should be made from stainless steel for durability
  4. Users need to fill a kettle easily from a shallow sink, so the design must allow filling with limited vertical clearance Correct answer.

Explanation

A usable problem statement names the user need and the constraint that makes it a problem, giving the designer something to design against. It states who is affected, what they are trying to do and the limiting condition, rather than jumping to a solution or a sales remark.

Question 28Design process, problem identification and specification

A designer is analysing the brief for a school bag aimed at students aged 11 to 16. Which item is a constraint rather than a performance requirement?

  1. The bag must be manufactured on the company's existing sewing line Correct answer.
  2. The bag must carry a 5 kg load without strap failure
  3. The bag must be openable with one hand
  4. The bag must keep contents dry in moderate rain

Explanation

A constraint is a fixed limit imposed by the manufacturer, market or law that the design cannot change, such as the available production equipment. Performance requirements describe what the product must do for the user and can be met in several ways.

Question 29Design process, problem identification and specification

A designer wants to establish the range of grip sizes needed for a new pair of secateurs. Which data source is most appropriate?

  1. Average measurements taken from five colleagues in the studio
  2. Marketing reports on how often secateurs are purchased
  3. Published anthropometric percentile data for hand breadth and grip circumference Correct answer.
  4. The designer's own hand measurements taken with a ruler

Explanation

Anthropometric percentile data gives a statistically representative spread of a population, allowing the designer to accommodate a defined proportion of users. Small convenience samples or a single person's measurements do not represent the target population reliably.

Question 30Design process, problem identification and specification

A designer is preparing a questionnaire to identify problems with an existing hand-held mixer. Which question design yields the most useful data?

  1. 'What do you think about the mixer?' with a blank space
  2. 'How often does the mixer feel too heavy to hold during use?' with frequency options Correct answer.
  3. 'Would you recommend this mixer to a friend?' with yes/no answers
  4. 'Do you agree the mixer is a good product?' with yes/no answers

Explanation

Effective survey questions target a specific, observable behaviour or difficulty and offer defined response categories that can be compared across respondents. Broad opinion prompts or simple yes/no satisfaction questions produce data that is hard to act on.

Question 31Design process, problem identification and specification

A design team builds a full-size mock-up of a checkout counter from cardboard and tape. Which evaluation purpose does this model serve best?

  1. Assessing the manufacturing cost of the counter
  2. Confirming the counter's structural strength under load
  3. Testing the reach and clearance for a seated operator Correct answer.
  4. Verifying the final surface finish and colour match

Explanation

A low-fidelity mock-up is suited to checking spatial relationships such as reach envelopes and clearances at full size, before detailed engineering. Cardboard cannot demonstrate structural performance, finish or production cost.

Question 32Design process, problem identification and specification

A designer scores four concepts against criteria, but two criteria are rated as equally important when one concerns user safety and the other concerns colour choice. What is the main weakness of the evaluation?

  1. The concepts were scored using a numerical scale
  2. Too many concepts were compared at once
  3. The criteria were not weighted to reflect their relative importance Correct answer.
  4. The evaluation did not include a prototype

Explanation

Weighted evaluation requires criteria to be ranked or weighted so that the scores reflect how much each requirement matters. Treating a safety criterion and a cosmetic criterion as equally important distorts the outcome in favour of concepts that are merely attractive.

Question 33Design process, problem identification and specification

A client brief asks for a lamp that is 'suitable for students'. Which action best begins the process of turning this into design criteria?

  1. Copy the specification of the best-selling lamp on the market
  2. Ask the client to write the full specification without designer input
  3. Research how students study, then define measurable requirements such as illuminance and adjustability Correct answer.
  4. Choose a lamp style the designer personally prefers and proceed

Explanation

An ambiguous brief is resolved by gathering evidence about the actual users and context, then converting needs into measurable criteria the design can be tested against. Personal preference, copying competitors or abdicating responsibility does not establish the real requirements.

Question 34Design process, problem identification and specification

A designer is producing a specification for a children's toy and must decide which criteria are essential. Which reasoning best justifies classifying a legal safety requirement as a demand?

  1. It is easy to test, so it should be treated as a demand
  2. The client mentioned it first in the brief, so it takes priority
  3. Failure to meet it makes the product illegal to sell, so it cannot be traded off Correct answer.
  4. Children's toys are usually colourful, so safety is a minor concern

Explanation

Demands are the non-negotiable requirements whose failure makes the design unacceptable, and legal obligations are the clearest example because the product cannot be sold without them. Ease of testing or the order items appear in a brief does not determine whether a criterion is mandatory.

Question 35Design process, problem identification and specification

A designer uses a Gantt chart when planning a product development project. Which benefit does this tool provide that a simple task list does not?

  1. It calculates the manufacturing cost of each component
  2. It guarantees the project will finish on schedule
  3. It replaces the need for a product design specification
  4. It shows tasks against a timeline with durations and overlaps Correct answer.

Explanation

A Gantt chart plots activities along a time axis, showing start and end dates, durations and where tasks run in parallel or depend on each other. It is a planning and monitoring aid, not a guarantee of schedule or a substitute for specification work.

Question 36Design process, problem identification and specification

A designer is analysing why a previous product failed in the market. Sales data shows strong early interest but high return rates citing 'too fiddly to use'. Which conclusion is best supported?

  1. The product attracted buyers but failed on usability in real use Correct answer.
  2. The marketing campaign was ineffective at reaching customers
  3. The product's packaging was unsuitable for retail display
  4. The product was priced too highly for the target market

Explanation

Strong early sales show the product appealed at the point of purchase, while returns citing difficulty of use point to a gap between expectation and actual interaction. The evidence supports a usability failure rather than a pricing, promotion or packaging problem.

Question 37Design process, problem identification and specification

A designer writes the criterion 'the drill must be easy to use'. Which revision makes it most suitable for inclusion in a product design specification?

  1. The drill must feel pleasant in the hand
  2. The drill must be designed for comfortable use
  3. The drill must be operable with one hand by 90% of tested users within 30 seconds Correct answer.
  4. The drill must be better than competitor models

Explanation

A specification criterion should be measurable so that it can be verified against the finished design. Stating the proportion of users, the task and the time limit gives an objective test, whereas vague adjectives cannot be evaluated consistently.

Question 38Design process, problem identification and specification

A designer needs to determine which of two competing requirements should drive the concept for a low-cost water filter for rural households. Requirement A: remove 99.9% of pathogens. Requirement B: retail below a set price. Which approach best resolves the conflict?

  1. Average the two requirements and design to the midpoint
  2. Prioritise pathogen removal, then optimise the design to meet the price as far as possible Correct answer.
  3. Prioritise the price target, then add filtration if budget allows
  4. Ignore both and design the most technically advanced filter

Explanation

Where a requirement concerns user health it functions as a demand that must be met, and the remaining requirements are then optimised within that boundary. Sacrificing pathogen removal for cost would make the product unfit for its purpose, and averaging demands is not a valid trade-off.

Question 39Design process, problem identification and specification

A design team claims its new packaging is 'sustainable' in the specification. Which revision best makes the claim verifiable during evaluation?

  1. The packaging must be made from paper rather than plastic
  2. The packaging must use at least 80% recycled content and be recyclable in kerbside collection Correct answer.
  3. The packaging must use less material than the previous version
  4. The packaging must look natural and environmentally friendly

Explanation

A verifiable criterion specifies a measurable threshold and the conditions under which it will be checked, so the finished design can be assessed objectively. Appearance, relative material reduction or a named material do not by themselves demonstrate environmental performance.

Question 40Design process, problem identification and specification

A designer must choose between gathering data from a large online survey and from observing ten users completing a task. Which statement best justifies using both methods together?

  1. The survey provides breadth of opinion while observation reveals actual behaviour, so together they give a fuller picture Correct answer.
  2. Observation is always more reliable, so the survey is only needed to increase the sample size
  3. The survey is more scientific, so observation should be used only to illustrate the findings
  4. Using two methods guarantees the conclusions will be correct

Explanation

Survey data reaches many respondents and shows the spread of reported views, while observation captures what users actually do, including difficulties they may not report. Combining them compensates for the weaknesses of each method, although no combination guarantees correct conclusions.

Question 41Materials, components and their properties

A designer needs a material for a transparent protective window on a machine guard. Which property combination is most important?

  1. High optical clarity with good impact resistance Correct answer.
  2. High water absorption with good thermal insulation
  3. High electrical conductivity with low thermal expansion
  4. High magnetic permeability with low hardness

Explanation

A machine guard window must let the operator see the process while resisting accidental impact, so optical clarity combined with toughness is the deciding requirement. Conductivity, permeability and water absorption do not relate to a transparent protective panel.

Question 42Materials, components and their properties

Which term describes the ability of a metal to be permanently stretched into wire without fracturing?

  1. Brittleness
  2. Stiffness
  3. Ductility Correct answer.
  4. Hardness

Explanation

Ductility is the property that allows a material to undergo permanent tensile deformation, which is exactly what drawing a metal into wire requires. Hardness resists indentation, stiffness resists elastic deflection, and brittleness means little plastic deformation before fracture.

Question 43Materials, components and their properties

A timber beam is loaded so that it bends. Which property most directly governs how much it deflects while staying within its elastic range?

  1. Toughness
  2. Modulus of elasticity Correct answer.
  3. Thermal conductivity
  4. Density

Explanation

Within the elastic range, deflection under a given load depends on the modulus of elasticity together with the section geometry. A higher modulus means less elastic deflection for the same stress. Toughness, density and thermal conductivity do not describe elastic bending behaviour.

Question 44Materials, components and their properties

Which material is a thermosetting polymer?

  1. Nylon
  2. Polyvinyl chloride
  3. Epoxy resin Correct answer.
  4. Polypropylene

Explanation

Epoxy is a thermosetting resin that cures by cross-linking into a rigid three-dimensional network, so it cannot be remelted. Polypropylene, PVC and nylon are thermoplastics that soften on heating and can be reshaped.

Question 45Materials, components and their properties

A component must resist repeated loading cycles without cracking over a long service life. Which property is being specified?

  1. Creep resistance
  2. Fatigue strength Correct answer.
  3. Surface hardness
  4. Impact toughness

Explanation

Fatigue strength is the ability of a material to withstand cyclic stress without initiating and propagating cracks. Creep concerns time-dependent deformation under sustained load, while impact toughness and hardness describe other loading conditions.

Question 46Materials, components and their properties

Which pair of properties is typical of ceramic materials used in engineering?

  1. High electrical conductivity and low hardness
  2. High hardness and low electrical conductivity Correct answer.
  3. High ductility and low melting point
  4. High toughness and high thermal expansion

Explanation

Engineering ceramics are generally hard, wear resistant and electrically insulating, which suits them to cutting tools and insulators. They are also brittle, so high ductility or high toughness is not characteristic.

Question 47Materials, components and their properties

Which test is used to determine the hardness of a metal specimen?

  1. Tensile loading to fracture
  2. Charpy pendulum impact
  3. Indentation under a controlled load Correct answer.
  4. Three-point bending to failure

Explanation

Hardness testing presses a defined indenter into the surface under a controlled load and measures the resulting impression, as in Brinell, Vickers and Rockwell methods. Tensile, impact and bend tests measure strength, toughness and flexural behaviour instead.

Question 48Materials, components and their properties

A product casing must be electrically insulating and easily injection moulded in large quantities. Which material best meets both requirements?

  1. Borosilicate glass
  2. Aluminium alloy
  3. Mild steel
  4. Acrylonitrile butadiene styrene Correct answer.

Explanation

ABS is a thermoplastic that is electrically insulating and flows well in injection moulding, making it a common choice for casings. Metals conduct electricity, and glass cannot be injection moulded in the same way.

Question 49Materials, components and their properties

A steel bracket is required to carry a load at 400 °C for several years. Which property should the designer check in the material data?

  1. Creep strength Correct answer.
  2. Magnetic permeability
  3. Fatigue limit
  4. Ductility

Explanation

At elevated temperature under sustained load, metals deform progressively by creep, so creep strength at the service temperature and stress is the relevant design property. Fatigue, ductility and permeability do not describe time-dependent high-temperature deformation.

Question 50Materials, components and their properties

Why is a thermoplastic such as polyethylene able to be recycled by remelting, whereas a cured epoxy cannot?

  1. Thermoplastics contain no carbon atoms in their chain structure
  2. Epoxies melt at a higher temperature than any thermoplastic
  3. Thermoplastics have linear or branched chains held by weak secondary forces, while cured epoxies have a covalently cross-linked network Correct answer.
  4. Thermoplastics are always amorphous and epoxies are always crystalline

Explanation

Thermoplastic chains are not chemically bonded to one another, so heating allows them to slide and the material to flow and be reshaped. In a cured thermoset, covalent cross-links form a permanent network that degrades rather than melts on heating.