Questions: Specifications and Requirements

Question 1

Which of the following is a well-written engineering requirement?

• A. The bridge should be strong
• B. The bridge must support a load of 5,000 kg without visible deflection exceeding 2 cm
• C. The bridge needs to be really safe
• D. The bridge should look nice

Answer: (B)

A good requirement is specific and measurable. 'Support 5,000 kg without deflection exceeding 2 cm' can be tested objectively. 'Strong,' 'really safe,' and 'look nice' are vague and subjective.

Question 2

A design requirement that can seldom be tested is still useful as a guiding principle.

• T. True
• F. False

Answer: False

If you cannot test whether a requirement is met, you have no way to verify the design succeeds. Untestable requirements should be rewritten as measurable statements or acknowledged as goals rather than requirements.

Question 3

What is the difference between a functional requirement and a performance requirement?

Model answer: A functional requirement states what the design must do (e.g., 'the pump must move water from tank A to tank B'). A performance requirement states how well it must do it (e.g., 'the pump must move at least 100 liters per minute').

Functional requirements define the capabilities a design must have. Performance requirements quantify how well those capabilities must be executed. Both are necessary for a complete specification.