ETC Technical Design & Engineering Principles 2 — Questions and Answers
Question 1: Which geometric dimensioning and tolerancing (GD&T) symbol specifies that a surface must lie between two parallel planes?
- Flatness (Correct answer)
- Straightness
- Perpendicularity
- Parallelism
Correct answer: Flatness
Flatness controls a surface by requiring all points to lie between two parallel planes separated by the tolerance value.
Question 2: In a hydraulic system, Pascal's Law states that pressure applied to a confined fluid is transmitted:
- Only in the direction of flow
- Equally in all directions (Correct answer)
- Proportionally to the fluid viscosity
- Only to the nearest wall
Correct answer: Equally in all directions
Pascal's Law states that pressure exerted on a confined fluid is transmitted undiminished equally in all directions throughout the fluid.
Question 3: A designer specifies a 'limit dimension' on a shaft diameter of 1.500/1.498 inches. What does this indicate?
- The nominal size is 1.499 inches
- The shaft may be any size between 1.498 and 1.500 inches inclusive (Correct answer)
- The tolerance is ±0.002 inches from 1.500
- The shaft must be exactly 1.499 inches
Correct answer: The shaft may be any size between 1.498 and 1.500 inches inclusive
Limit dimensioning specifies the maximum and minimum permissible sizes directly; any size within that range is acceptable.
Question 4: When designing for fatigue resistance, which surface treatment is most effective at extending a metal component's fatigue life?
- Annealing
- Shot peening (Correct answer)
- Electroplating
- Normalizing
Correct answer: Shot peening
Shot peening induces compressive residual stresses on the surface, which counteract tensile stresses that initiate fatigue cracks.
Question 5: On an engineering drawing, a hidden line is represented by:
- A continuous thick line
- A long dash-dot line
- A series of short dashes (Correct answer)
- A continuous thin line
Correct answer: A series of short dashes
Hidden lines (edges not visible from the viewing direction) are drawn as a series of short dashes per ASME Y14.2 line conventions.
Question 6: What is the primary purpose of a datum reference frame in GD&T?
- To specify surface finish requirements
- To establish a coordinate system from which measurements are made (Correct answer)
- To define the material condition of a feature
- To indicate the inspection sequence
Correct answer: To establish a coordinate system from which measurements are made
A datum reference frame establishes three mutually perpendicular planes that create a coordinate system for locating and orienting part features.
Question 7: Bernoulli's principle relates an increase in fluid velocity to:
- An increase in static pressure
- A decrease in static pressure (Correct answer)
- No change in static pressure
- An increase in fluid temperature
Correct answer: A decrease in static pressure
Bernoulli's principle states that as fluid velocity increases, its static pressure decreases, since total mechanical energy is conserved.
ETC Technical Design & Engineering Principles 2
Which geometric dimensioning and tolerancing (GD&T) symbol specifies that a surface must lie between two parallel planes?