Computer Aided Drafting Questions and Answers

Answer: A

Editing an existing geometry costs a fraction of redrawing it, which is what makes revision and design iteration practical. The conventions of projection, sectioning and dimensioning apply exactly as they did on the board, since the reader of the drawing has not changed.

Answer: B

A line held as two endpoints can be moved, trimmed and scaled without loss, whereas a grid of pixels degrades on every such operation. It is why CAD drawings are vector and scanned drawings must be vectorised before they can be edited properly.

Answer: C

Drawing everything at its real dimensions keeps the database a true model of the object, so any scale of output can be produced from it and queries return real lengths. Applying the scale at the plotter instead of in the geometry is the settled practice.

Answer: D

Each line, arc, text item and dimension is stored with its geometry, layer, colour and line type, and the display is generated from that store. Because the store is the drawing, it can be interrogated for lengths, areas and counts.

Answer: A

Correct answer: the origin of the coordinate system

Absolute entry gives the point’s position in the drawing’s own coordinate frame, measured from the origin regardless of where the cursor or the last point happens to be. Relative entry measures from the previous point instead, and confusing the two is the commonest way of placing geometry a long way from where it was meant to go.

Answer: B

A chain of known displacements maps directly onto relative entry, since each side is given as an offset from the previous corner. The drawback is that an error early in the chain carries through to every point after it, which absolute entry avoids.

Answer: C

Correct answer: a distance and an angle

Polar entry gives the length of the step and the direction it runs in, which suits geometry described by bearings or by an included angle. The two methods are complementary: rectangular entry suits work laid out on a grid, and polar entry suits work laid out by angle.

Answer: D

Aligning the axes with an inclined face lets coordinates be entered as though that face were orthogonal, which removes a great deal of trigonometry. The world coordinate system remains beneath it as the fixed reference for the whole model.

Answer: A

Putting centre lines, hidden detail, dimensions and hatching on their own layers lets each be given its line type and colour once and be turned off when not wanted. It is what makes one drawing serve several purposes without being redrawn.

Answer: B

Assigning the property to the layer means every entity on it follows automatically and a revision affects them all together. Overriding the property entity by entity is possible but scatters the control and makes later changes laborious.