Topics in Basic Technology
Types of chain drive Types of belt drive Types of Ceramics Advantages and Disadvantages of Chain Drives Len Academy Questions for Basic Technology JSS3, 2nd Term, 2020 Len Academy Question for Basic Technology, JSS3, 2nd Term, 2020, Part 2 Belt and Pulley Drives: Types of belt in belt drives Refrigerator as an electromechanical device, its parts and operations What is chain drive? Classification of chain drive What are Belt Drives? Advantages and Disadvantages of Belt Drives Type of Lines in Technical Drawings Len Academy questions for Basic Technology, JSS2, 2nd Term Len Academy questions for Basic Technology JSS2, 2nd Term, Part 2 What is Maintenance? Types of Maintenance Hardwood and Softwood - Characteristics and Examples What are Ceramics? Characteristics of Ceramics
Academic Questions in Basic Technology
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Which of the following is false concerning advanced ceramics?
A. They can be made from metallic oxides
B. They are very hard and durable
C. They are corrosion resistant
D. They are fired in the presence of oxygen
E. They are fired at a very high temperature of about 1700oC
F. They can be made from non-oxides such as carbides and borides
A thin continuous line is used for representing the followings except _____.
A. Intersections
B. Hatching lines
C. Long breaks
D. Diagonal line used to state plane surfaces
E. Leader lines
F. Back section lines
With regards to chain drives, the diagram above is a/an _____ chain.
A. Roller
B. Silent
C. Leaf
D. Flat-top
E. Detachable
F. Acceleration
A type of chain drive commonly used in bicycles is the _____ chain.
A. Roller
(Video) Hardwood vs Softwood |Quick Difference and Comparisons |B. Silent
C. Leaf
D. Flat-top
E. Detachable
F. Acceleration
A chain drive consists of an endless chain running over two _____.
A. Hooks
B. Spikes
C. Spokes
D. Sprockets
E. Hinges
F. Danes
Which is the most economical of all power transmitting drive mechanisms?
A. Pulley drive
B. Gear drive
C. Chain drive
D. Belt drive
E. Thread drive
F. Fabricated drive
Which of the following is false concerning drive mechanisms in machines?
A. Pulley drives do not require a means of power transmission
B. Gear drive is a means of power transmission
C. Chain drive is a means of power transmission
D. Belt drive is a means of power transmission
E. The drive mechanisms of machines accomplishes it's function via a rotational motion
F. Drive mechanisms results into a mechanical movements of machines via power transmission
The lines above are used at the end of dimension lines?
A. True
B. False
What is Wood?
Wood is derived from the stem, trunks and branches of trees.
A wood is an organic material and a structural tissue composed mainly of cellulose; and it constitutes the stem, roots and branches of trees.
You can read on the trees found in tropical rainforest here.
The outermost skin or covering of the wood is called the bark. On peeling off the bark, next to be seen is the sapwood which contains the plant's transport system called the xylem. Also seen inside the sapwood is the heartwood, but here, the xylem is blocked with gums; making it functionally inactive. The cambium is seen around the edge of the sapwood. This is shown in the image below:
We have two types of wood. These are:
Hardwood
Softwood
Generally, woods are porous and fibrous in nature. However, the terms 'hardwood and softwood' don't always refer to the wood's actual hardness or softness.
You can read on the roles of government in agriculture here.
Hardwood
Hardwoods are derived from angiosperms.
Angiosperms are flowering plants that produce seeds encased in fruits or pods.
Please read on the differences between gymnosperms and angiosperms.
Most times, hardwood are stronger than softwood but there are exceptions. For instance, balsa is a hardwood that is actually soft.
Characteristics of Hardwood
- They usually have a higher density than softwood. Balsa is an exception.
- They are usually more expensive than softwood.
- They grow at a slower rate than softwood.
- Hardwood trees shed their leaves in certain times of the year.
You can read on the differences between plants and crops here. - Hardwood are more fire resistant than softwood.
- The leaves of hardwood trees are evergreen.
- They are used for making quality furniture (in terms of strength). They are also suitable as deckings in buildings.
- Hardwood trees always have divided trunks which are often referred to as a dendritic form.
- In terms of price, hardwood are usually more expensive than softwood.
You can read on scale of preference and opportunity cost here.
Examples of hardwood include iroko, ash, beech, alder, teak, birch, mahogany, maple, oak, balsa and walnut.
You can attempt Len Academy examination questions for JSS2 basic technology here.
Softwood
Softwoods are often derived from coniferous trees, that is: trees with needle-like leaves, and whose seeds are covered in cones.
Note: Coniferous trees are classified under gymnosperms.
Please read on the anatomical and structural differences between gymnosperms and angiosperms here.
Characteristics of Softwood
- Most softwood have lower densities than hardwood (weighs lower).
Please read more on density here. - In terms of price, they are often less expensive than hardwood.
- Their growth rate is faster than hardwood.
- Most softwood do not shed their needle-like leaves during the year. However, the softwood 'larch' and 'cypress' are exceptions.
- They are less fire resistant.
- Their leaves are evergreen, just like hardwood.
- Softwood serve various purposes; For instance many doors, windows and papers are made from softwood.
- They normally have a single dominant trunk referred to as excurrent form.
- Softwood trees are usually tall and straight.
- Most are cheaper than hardwood.
You can read on the characteristics of ceramics here.
You can read on interesting facts for students here.
Examples of softwood include cedar, larch, juniper, yew, cypress, fir, pine, spruce, douglas fir and redwood.
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Amazing facts in Basic Technology
Rubber bands last longer when refrigerated
Lighter was invented before matches
Johann Wolfgang Dobereiner was credited with the invention of lighter in 1826 while the match was made 3 years later
Volkswagen group of companies own some of the top cars of the world. These are Audi, Bentley, Bugatti, Ducati, Lamborghini and Porsche
NOTABLE POINTS IN Basic Technology
Arrowhead lines are lines with pointed edges at one or both ends. The pointed edges are in the form of an arrow.
Arrowhead lines are used:
At the end of dimensional lines.
As measurement lines.
Please read more on types of line here.
A thin continuous line could be a straight or curved line. However, the main point to remember is this: 'it is a tiny line with no dot or dashes within it'.
_______________________
A thin continuous line is used for representing the followings:
Projection lines
Hatching lines
Construction lines
(Video) Difference Between Hardwoods and Softwoods I uses I color I texture IShort center lines
Measurement lines
Diagonal lines used to state plane surfaces
Intersections
Leader lines
Backside section lines
Any action that involves the servicing, checking, replacing and repairing of an equipment, object or device is termed maintenance.
Maintenance has two main goals. These are:
To prevent a breakdown
To repair the breakdown
Below are the types of maintenance:
Preventive maintenance
Corrective maintenance
Predictive maintenance
Periodic maintenance
Reinforcement
Overhaul
Please read more on maintenance here.
Softwoods are often derived from coniferous trees, that is: trees with needle-like leaves, and whose seeds are covered in cones.
Below are some characteristics of softwood:
Most softwood have lower densities than hardwood (weighs lower).
In terms of price, they are often less expensive than hardwood.
Their growth rate is faster than hardwood.
Most softwood do not shed their needle-like leaves during the year. However, the softwood 'larch' and 'cypress' are exceptions.
They are less fire resistant.
Please read on hardwood and softwood here
The diagram below shows the various types of line in technical drawing, their description and general application:
Please read more on the types of line in technical drawing here