Topics in Basic TechnologyCeramics: 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 Electromechanical Energy: Parts of the Refrigerator and how they operate Chain Drive, Types, Classifications, Advantages and Disadvantages 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 Maintenance, Types of Maintenance Hardwood and Softwood - Characteristics and Examples What are Ceramics? Characteristics of Ceramics
Academic Questions in Basic Technology
Which of the following is not a type of maintenance?
Which of the following is incorrect concerning preventive maintenance?
A. It is considered to be the best form of maintenance
B. Immunization is a form of preventive maintenance
C. Worn out parts may be discovered when preventive maintenance is carried out
D. Preventive maintenance is defined as the repairs carried out on an equipment or object after a correct prediction of an impending fault
E. A person who services his car monthly practices preventive maintenance (even though the car functions properly)
F. The main goal of preventive maintenance is to stop a device from breaking down suddenly
The following statements are true concerning wood except _____.
A. It is an inorganic material
B. It is a structural tissue
C. It is composed mainly of cellulose
D. Hardwood and Softwood are types of wood
E. It constitutes the stems and branches of trees
F. It is porous and fibrous
Which of the following is not a characteristic of hardwood?
A. They are more fire resistant in comparison to softwood
B. Their stem are divided into trunks called dendritic form
C. Birch, Teak and Alder are examples of hardwood
D. They always have a higher density than softwood of the same mass
E. They are suitable for making deckings in buildings
F. Most hardwood are expensive than softwood
The outermost covering of a wood is called the _____.
A. Wood skin
The followings are characteristics of ceramics except _____.
A. They readily undergo oxidation
B. They have high melting point
C. They are durable
D. Most are insulators but graphite is a conductor of electricity
E. Most are non-magnetic
F. They have great tensile strength but graphite is soft
Which of the following statement is false of ceramics?
A. They are not metals
B. They are not plastics
C. Ceramics can be absolutely defined by its products characteristics
D. Ceramic materials are not organic in nature
E. Ceramics are refractory in nature
F. Ceramics materials are usually made from clay
Which of the following is not a function of thin continuous line in Technical drawing?
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Belt drives are one of the drive mechanisms or transmissions employed in machines to bring about mechanical movement via power transmission.
It is important to understand that the most ideal and simplest form of transmitting mechanical power is via the rotational motion; and the belt drive proves to be very useful here.
As an instance, a pepper grinder uses a drive (in the form of a belt) to propel forward its shaft.
Similarly, a sewing machine utilizes a belt (as its drive); and it can be mechanically moved via the "foot actions" of the tailor.
The image below shows a belt drive connecting two pulley systems:
From the diagram, we can see that the belt drive requires a belt as its mechanism for mechanical power transmission.
Apart from belt drives, Other methods of mechanical power transmission includes:
In the drive system, the machines are driven by rotational motion through its shaft to the other parts around it.
The driving pulley of the machine is termed the Driver System while that which is driven is termed the Driven System.
Note: A pulley is a wheel or sets of wheel over which a belt or chain is attached in order to create a movement or motion.
Below are the various type of belt drives that are often used alongside a pulley system:
The open belt drive is used when two parallel shaft are needed to rotate in the same direction.
When the open belt drive is in used on a widely separated shaft, the upper side of the belt must be the slack side while the lower side becomes the tight side.
Note: If we made the upper side the slack side (in a separated shaft), sagging will occur and the contact arc will be increased.
The cross belt drive is used when two parallel shaft are needed to rotate in the opposite direction.
Due to the crossing nature of this belt, the belts rub against itself at a specific junction, resulting to its wearing off and eventual damage.
Note: In order to reduce the excessive wear caused from the meeting point of the crossed belts, the shafts should be placed at an optimum distance from each other; while been operated at low speeds.
A fast and loose pulley drive is often used when the driven pulley is required to be started or stopped without creating an interference with the driving pulley.
Note: The pulley keyed to the machine shaft is referred to as the fast pulley.
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Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.
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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 actual 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
Preventive maintenance is carried out routinely on a device even though no apparent fault may be present on such device.
The goal of preventive maintenance as the name suggest is to prevent a sudden breakdown on a device or equipment.
As an instance, a person who services his or her car monthly even though the car is still able to function correctly is said to be carrying out preventive maintenance on the car.
In the course of a preventive maintenance, worn out parts may be discovered and replaced as soon as possible. Also, there may be a change of oil while other little adjustments may also be carried out.
We can even carry out preventive maintenance on our body to prevent certain diseases. For this reason, some persons have discovered cancerous cells in their body through regular medical checkup; and were able to kill such cells before they become malignant.
As a matter of fact; immunization is a form of preventive maintenance.
Hardwoods are derived from angiosperms. They show the following characteristics:
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.
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 for decking in buildings.
Hardwood trees always have divided trunks which are sometimes referred to as a dendritic form.
In terms of price, hardwood are usually more expensive than softwood.
Examples of hardwood include iroko, ash, beech, alder, teak, birch, mahogany, maple, oak, balsa and walnut.
Ceramics are refractory. They also require a very high amount of heat and subsquent cooling to be formed.
Being refractory means that they are capable of withstanding a variety of abuses like high temperatures and chemical attacks.
Ceramics are generally made by taking clay from the ground and mixing it with water. It is then shaped into any form and fired inside an oven (called kiln) at a very high temperature. They may then be decorated with a waterproof, paint-like substances called glazes.
Ceramics may have constrasting physical and chemical properties (or characteristics); but in general,
They have high melting points.
They are heat resistant.
They can be very hard with great strength; although a few are brittle or soft; for example, graphite.
They are durable (last for a long time).
Most are electrical insulators (cannot conduct electricity) but; graphite is an electrical conductor.
They are chemically unreactive or inert.
They are not easily oxidized.
Most are non-magnetic.