Projections of Solids Questions and Answers

Answer: C

Correct answer: a square of the true base size

With the axis vertical the base lies flat on the horizontal plane, so it is projected without foreshortening and appears in the plan at true size and shape. The lateral edges project onto the corners of that square and the axis onto its centre. Foreshortening would occur only if the base were inclined to the plane of projection.

Answer: D

Correct answer: a point

A line perpendicular to a plane of projection projects onto it as a single point, since every part of the line falls on the same spot. So a vertical axis appears as a point in the plan, at the centre of the base figure, while it shows its true length in the elevation. The same rule identifies a vertical edge or a horizontal generator.

Answer: A

The simple position is drawn first with the base on the horizontal plane, and the views are then redrawn with the axis tilted to the stated angle. Attempting the inclined position directly is what makes such problems go wrong.

Answer: B

Correct answer: on the horizontal plane, axis vertical

The staged method always begins with the solid in its simple position, base on the horizontal plane and axis vertical, because only there is the base drawn in true shape and size. The inclination is then introduced by tilting the whole first-stage drawing, which carries the true base shape into the new position without redrawing it.

Answer: C

Correct answer: three stages of drawing

With the axis inclined to both planes the drawing proceeds in three stages: first the simple position with the axis vertical, then a tilt giving the required inclination to the first plane, then a turn giving the inclination to the second. Each stage is projected from the one before, which is what keeps the true shapes correct.

Answer: D

Correct answer: parallel to one principal plane and in the other

Resting on a base edge means that edge lies in the horizontal plane, and it is drawn parallel to the vertical plane so that it appears in true length in the elevation and the tilt can be measured. The base is then inclined to the horizontal plane, touching it along that line rather than over its whole area.

Answer: A

Correct answer: inclined to the horizontal plane

Resting on a corner means the base touches the horizontal plane at a single point, so the base cannot be lying flat - it must be inclined to the plane. The three resting positions form a sequence: on the base, and the base is parallel to the plane; on an edge, and it touches along a line; on a corner, and it touches at a point.

Answer: B

A generator lying in the horizontal plane means the axis is parallel to that plane at a height equal to the radius. The plan is then a rectangle and the elevation a circle if the axis is also perpendicular to the vertical plane.

Answer: C

Correct answer: behind another surface as seen in that view

An edge is hidden when some face of the solid lies between it and the observer in that particular direction of viewing, so the same edge may be visible in one view and hidden in another. Being at the outline guarantees visibility, and lying in or parallel to the plane of projection has no bearing on whether it can be seen.

Answer: D

Correct answer: always drawn as a visible line

The outline is the silhouette of the solid in that view, so by definition nothing lies in front of it - it is always visible and always drawn as a continuous thick line. It is the edges within the outline that must be judged one by one, and drawn dashed where a face lies in front of them.