# Machine Drawing Questions and Answers – Types of 3D Model

«
»

This set of Machine Drawing Multiple Choice Questions & Answers (MCQs) focuses on “Types of 3D Model”.

1. The model which is created by using basic entities of two dimensioning is called __________
a) Surface model
b) Wire frame model
c) Solid model
d) Isometric model

Explanation: The model which is created by using basic entities of two dimensioning is called as wire frame model. Wire frame model is made by using two dimensional basic entities such as points, straight lines, curves, polygons, circles, etc. The model shows like a frame constructed out of wire and hence it is called a wire frame model.

2. Types of models which is commonly used are ___________
a) Simple model
b) Composite model
c) Isometric model
d) Solid model

Explanation: The types of models which are commonly used are Solid model, Surface model and wire frame model. The wire frame model are the simplest form of models which are used in drawing This model is draw with the help of two dimensional basic entities are line, rectangle, cycle, curves and polygons etc.

3. In which of the types of wire frame model is used for drawing flat objects?
a) 2D wire frame model
b) 2.5 wire frame model
c) 3D wire frame model
d) Solid model

Explanation: In 2D wire frame model the flat objects are to be drawn. 2.5 wire frame model represents three dimensional objects as long as it does not have side wall details. 3D wire frame model is used for three dimensional representations of objects with side wall details.

4. The __________ form the basis for surface models.
a) surface model
b) solid model
c) wire frame model
d) isometric model

Explanation: The wire frame models form the basis for surface models. The wire frame model is easy and simple to construct. The wire frame model requires less computer memory for storage compared to surface and solid model.

5. The wire frame entities are _________
a) Plane surface
b) Ruled surface
c) Tabulated surface
d) Polygons

Explanation: The basic wire frame model geometric entities are analytic entities and synthetic entities. The analytic entities are points, lines, arcs, circles, fillets, chamfers, and conics. The synthetic entities are various types of splines and Bezier curve.

6. The representation of complex objects which is not be drawn by wire frame model is called as ____________
a) Surface model
b) Wire frame model
c) Solid model
d) Isometric model

Explanation: The representation of complex objects such as automotive bodies, aircraft bodies, ship bodies, castings, and dies cannot be achieved by wire frame modeling. In such cases, another method of geometric modeling used is known as surface modeling.

7. The surface model is created by using ___________
a) Analytic entities
b) Synthetic entities
c) Analytic and Synthetic entities
d) Basic entities

Explanation: A surface model is generated by using wire frame entities i.e. analytic and synthetic. A system may require one wire frame entity to create a surface of revolution or it may require two wire frame entities to create a ruled surface.

8. What is the basic part of the surface model on which the surface is to be drawn?
a) Ruled
b) Ruler
c) Size
d) Mesh

Explanation: The mesh is the basic part of the surface model on which the surface is to be drawn. IN order to assist the visualization of a surface on a graphics display, artificial fairing lines, called mesh are added on the surface. The mesh size is controlled by the user.

9. The surface form used to model an aircraft body may not be sufficient to model the human heart.
a) True
b) False

Explanation: The surface form used to model an aircraft body may not be sufficient to model the human heart. The choices of the surface are chosen according to the application. The types of surfaces are used in surface modeling are ruled surface and plane surface.

10. The basic surface modeling entities are ____________
a) Polygons
b) Circle
c) Surface of revolution
d) Chamfers

Explanation: The basic surface model entities are ruled surface, tabulate surface, plane surface, Bezier surface, B-spline surface, coons patch, fillet surface and offset surface. The basic wire frame entities are circle, polygons and chamfers.

11. The surface which is not to be drawn by the surface model drawn by __________
a) Surface model
b) Wire frame model
c) Solid model
d) Isometric model 