Two Marks Questions and Answers

TWO MARKS QUESTIONS AND ANSWERS

 

1. What is a timber?

Timber represents wood which is appropriate for carpentry, building and for various engineering purposes. Timber is a fibrous, hard substance which forms a most part of the trunk and branches of a tree.

2. Write about rough timber and converted timber.

If the branches of a tree are cut and is approximately converted into pieces of required length, then it is known as rough timber. Through sawing, rough timber is converted into different marketable parts like planks, battens, posts, beams etc. then it is called as converted timber.

3. Enumerate the various market forms of timber.

The followings are the various types of market forms of timber.

❖ Log

❖ Lumber

❖ Deal

❖ Batten

❖ Bilk

❖ Plank

❖ Board

❖ Scantline

❖ Pole

4. List any four properties of timber.

The following are some of the properties of a good timber:

❖ Colour: Colour should be uniform.

❖ Odour: When freshly cut, odour should be pleasant.

❖ Texture: Good timber should have fine and even texture.

❖ Grains: Grains are close in good timber.

❖ Density: If density is more, timber is said to be stronger.

5. What is water seasoning?

Removal of wood sap by immersing logs into water flow is called water seasoning. It is carried out on the river banks while thicker ends are kept towards 10 upstream. After that, the logs are allowed to dry. This process is time consuming 00 such as 2 to 4 weeks generally.

6. List any four characteristics of timber.

The Characteristics of timber are,

❖ Hardness.

❖Strength.

❖Toughness.

❖ Elasticity.

❖Durability.

❖ Defects.

❖ Fibres and structure.

❖ Appearance and colours.

7. What is a cup shake in timber?

Cup shakes are caused by the rupture of tissue in a circular direction. It is a curved crack, and it separates partly one annual ring from the other developing one due to non-uniform growth or due to excessive bending of a growing tree during a cyclonic weather. It may prove to be harmful if it covers only a portion of the ring.

8. Give some of the uses of Timber.

Timber is used for the following purposes:

❖ Timber is widely used for doors, windows, flooring and roofing as it is easily convertible into any shape and size.

❖ It can be easily worked. Hence repairs and alterations to wood work can also be done easily.

❖ It possesses excellent strength and a good preference for making load bearings like columns, beams, trusses and piles.

❖ Timber is widely used in ornamental works like showcases, furniture, sports goods and musical instruments

9. Define Plywood.

grime Plywood is an engineered wood sheet material made up of fine layers or flimsy strands of wood veneers attached together by placing wood grains 90 degrees to one another. It is one type of mar ufactured board which can be described as a mixture of medium density fibre board (MDF) and Chip Board (Particle Board).

10. What are the uses of Plywood?

❖ It has good strength both along as well as across the grains and are extensively used for partitions, ceilings, doors, concrete form work, plywood boards, lamin boards etc.

❖ It has better splitting resistance due to the grains in adjacent veneers in cross direction as such nailing can be done very safely even near the edges.

❖ Plywood has cross-grained construction, the tendency to shrink or swell is reduced and hence it can be curved into desired shapes.

11. What are the different ways of slicing of veneer?

Different ways of slicing wood to get veneers are as follows:

Rotary cut: The log is cantered on a lathe and turned against a broad cutting knife set into the log at a slight distance.

Quarter slicing: The slicing is made perpendicular to the annual growth rings of the tree. This creates a straight grain appearance.

Lengthwise slicing: This is done from a board of flat sawn lumber rather than from a log. A variegated figure is created with this slice.

Plain slicing: By slicing parallel to the centre of the log, a raised "cathedral o effect" is formed by the innermost growth rings.

12. List the advantages of false ceiling.

The advantages of false ceiling are:

❖ False ceiling materials are easy to install and cheap as compared to traditional roof systems and also gives aesthetic appearance.

❖ It provides a smooth homogeneous surface to the roof and helps in acoustics.

❖ It conceals all the non-pleasing elements and hides it from the viewer's eyes.

❖ It provides fire protection as it separates the roof.

13. What are the common defects in steel?

The common defects in steel are as follows:

❖ Cavities or blow-holes

❖ Cold shortness

❖ Red shortness

❖ Segregation

14. Name the constituents of glass.

The constituents of glass are,

❖ Silica

❖ Oxides of lead

❖ Oxides of Cobalt

❖ Oxides of Manganese

15. Mention the application of fibre glass reinforced plastic.

The most important application of fibre glass reinforced plastics is said to be in the manufacture of corrugated sheeting, mainly for use in roof lights and also for interior paneling and decoration.

16. Define the term Refractories.

A refractory material is a material that retains its strength at high temperatures. Refractory materials are used in for furnaces, kilns, incinerators, and reactors. They are also used to make crucibles and moulds for casting glass and metals and for surfacing flame deflector systems for rocket launch structures.

17. Write the properties of refractories.

Physical properties

(i) Bulk density (ii) Porosity (iii) Cold compressive strength (iv) Flexural strength (v) Wear resistance

Chemical properties

(i) Corrosion resistance

Thermal properties

(i) Melting point (ii) Thermal expansion (iii) Dimensional stability (iv) Thermal shock (v) Thermal conductivity.

18. Name any four merits of aluminum in construction?

❖ High corrosion resistance

❖ Safety against attack from insects

❖ Economy in maintenance

❖ Aesthetic appearance

❖ Ease in fabrication and assembly

19. List the operations involved in the mechanical treatment of steel.

Following are the operations involved in the mechanical treatment of steel:

❖ Drawing

❖ Forging

❖ Pressing

❖ Rolling

20. Give some of the uses of aluminium.

Uses of Aluminium are

❖ Aluminum is used in external facades, roofs and walls, in windows and doors, in staircases, railings, shelves, and other several applications.

❖ Aluminium is widely used in the packaging industry for the production of coils, cans, foils, and other wrapping materials.

❖ Aluminium bronze is used for pump lines, tubes, springs, screws, rivets, ornamental works, marine engineering castings, motor boat shafting, musical instruments, and as a substitute of mild steel to resist corrosion, grill works, etc

21. Define laminates.

Laminates are the products made by bonding together of two or more layers of materials. Special laminates from plastics are also available in the market. These can be glued to wood to make the surface aesthetic as well as heat- resistant.

22. What are geo synthetics?

Geo fabrics are also called geo synthetics or geotextiles. These are synthetic fabrics which are sufficiently durable to last a good length of time in soil environment used in geotechnical engineering.

 23. List the uses of ceramics.

Some of the uses of ceramics are listed below:

❖ Ceramic products are hard, porous, and brittle. As a result, they are used to make pottery, bricks, tiles, cements, and glass.

❖ They are used in automobiles for sparkplugs and ceramic engine parts found in racecars and phone lines.

❖ They can also be found on space shuttles, appliances as enamel coatings, and airplanes in nose cones.

24. Define FRP.

Fiber-reinforced plastic (FRP) composites have transformed the manufacturing sector. FRP composites offer high-end performance at a fraction of the weight and cost of comparable metal materials. Construction, energy, aerospace, and other critical sectors are realizing the benefits of FRP for producing reliable parts and components.

25. What are the applications of FRP Composites?

Some of the common applications for FRP materials include:

❖ These are widely used in public works like commercial, industrial, and municipal applications

❖ FRP are used in wood replacement like Benches, Boardwalks, Decks, Fences, Rampsia

❖ They have also wide application in Military (Navy) and Mining works

❖ FRP are used in Concrete forming (reusable) and Construction works like Flooring, Roofing and Pergolas