# Solid Modelling MCQ – Set 7

This set of Solid Modelling Multiple Choice Questions & Answers (MCQs) focuses on “Solid Entities”.

1. Which of the following are the most commonly used primitives to create a solid?
a) Cone, sphere, wedge, torus
b) Block, cylinder, wedge, torus
c) Block, cylinder, cone, sphere
d) Cylinder, cone, sphere, Torus

Explanation: The four most commonly used primitives to create a solid are block, cylinder, cone, sphere. These are based on four natural quadrics that are planes, cylinders, cones and spheres. These quadrics are considered natural because they represent the most commonly occurring surfaces in mechanical design.

2. What are the inputs required to define the primitive of solid completely?
a) Set of location data
b) Set of geometric data
c) Set of location and geometric data
d) Set of location, orientation and geometric data

Explanation: From a user point of view, a primitive requires set of location, orientation and geometric data to define it completely. Location data involves a primitive local coordinate system. Orientation data is used to orient primitive properly. Geometrical data differs from one primitive to another and is user input.

3. Which of the following Boolean operators are used while performing Boolean operations on primitives of solid?
a) Union, intersection, difference
b) Union, intersection
c) Intersection, difference
d) Union, difference

Explanation: While performing Boolean operations on primitives of solid, the Boolean operators used are union, intersection, difference. The union operator is used to combine or add together two primitives. Intersection of two primitives gives a shape equal to their common value. The difference operator is used to subtract one object from another.

4. Natural quadrics used to build primitives of a solid are combination of linear motion and rotation.
a) True
b) False

Explanation: In order to build primitives of a solid, natural quadrics that are planes, cylinders, cones and spheres are required to translate and rotate to position and orient properly. Therefore, natural quadrics are combination of linear motion and rotation. Other primitives, except torus, require dual axis control.

5.Which of the following is not the standard Constructive Solid Geometry (CSG) primitive?
a) Cube
b) Box
c) Triangular prism
d) Torus

Explanation: The standard Constructive Solid Geometry primitives consist of cube, sphere, cylinder, cone, triangular prism and torus. They require geometric transformations to create the final solid. Box is not represented as a part of CSG primitives while designing as it does not lead to the required shape.

6. What geometrical data input is required to define the cylinder in solid modelling?
a) Width, height, depth
d) Total length

Explanation: In order to define the cylinder primitive, geometrical inputs required are radius and height. The height is usually taken along the z-axis and can be positive or negative. Negative value of height is displayed as if the cylinder is mirrored about the same positive value of height.

7. Which of the following primitives are axisymmetric in solid modelling?
a) Block, cylinder, wedge
b) Cone, sphere, torus
c) Block, cylinder, torus
d) Cone, block, wedge

Explanation: The cone, sphere and torus are axisymmetric primitives in solid modelling whereas the remaining primitives that are block, cylinder and wedge are of uniform thickness. All these primitives can be generated using feature approach and user can generate them via sketching.

8. Which of the following solid primitive does not need radius as the input geometrical data?
a) Torus
b) Cone
c) Wedge
d) Sphere

Explanation: The geometry of torus, cone and sphere is defined using the radius as one of the inputs. Wedge is the solid primitive which needs height, width and base depth as input geometrical data and it is of uniform thickness. Its geometry does not consist of any radius.

Sanfoundry Global Education & Learning Series – Solid Modelling.