Lesson Notes By Weeks and Term - Junior Secondary School 3

TERM: 2ND TERM

SUBJECT: BASIC SCIENCE

CLASS: JSS 3

REFRENCES

• Basis Science Made Easy for JSS Three by F.I Kehinde et al
• Basis Science Made Easy for JSS Two by F.I Kehinde et al
• STAN Integrated Science for JSS Three
• Precious Seeds Basic Science for JSSThree by J.O Otugboyega et al.

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WEEK EIGHT

TOPIC: SIMPLE MACHINE

CONTENT

• Definitionof Simple Machine�
• Types of Machine
• Importance of Simple Machine

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Definition of Simple Machine�

A machine is a tool or device that makes work easier. It is defined as a tool which uses force applied (effort) at one point to overcome another resisting force (effort) at another point. Examples of machine include: a plier, the human arm, a gear, a pulley etc.

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Types of Machine

There are six types of simple machines. They are;

1. Lever
2. Wheel and axle
3. Pulley
4. Wedge
5. Inclined planeScrew
6. Screw

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Lever

A lever is a simple machine built on the principle of a stiff bar resting on a pivot or fulcrum with a load placed at one end and effort applied on the other end.�

There are three parts of the lever;

1. Load: This is the point of the resisting force.
2. Effort: This is the point where force is applied.
3. Fulcrum: This is the turning point of the lever.

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Types of Lever

There are three classes or order of lever. They are;

• First Order Lever: In this lever, the fulcrum is between the load and effort (LFE). Examples include:� scissors, claw hammer.
• Second Order Lever: In this lever, the load (L) is between the effort (E) and the fulcrum (F) (FLE). Example of this including; wheelbarrow, nutcracker, bottle opener etc.
• Third Order Lever: In this lever, the effort is between load and effort. (FEL). Example of this include; fore arm.

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Wheel and Axle

This simple machine is used to lift heavy load from depth. It consists of a Large wheel on a small axle that turns in the same axis. Examples of wheel and axle include: bicycles, fan, wagon etc.

Use

1. It is used to draw out heavy load from depths
2. It is used to create the turning effects in bicycle

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EVALUATION

• Define simple machine.
• List two uses of (a) Lever� (b)Wheel and Axle.

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Pulley

A machine consisting of a wheel over which a pulled rope or chain runs to change the direction of the pull used for lifting a load. Combinations of two or more pulleys working together reduce the force needed to lift a load.

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Uses

1. It is used lift and move load in cranes
2. It is also used in lifts (elevators)

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Wedge

A wedge is a triangular shaped tool, and is a portable inclined plane. It can be used to separate two objects or portions of an object, lift up an object, or hold an object in place.

Use

It is used to split objects open especially wood.

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Screw

A screw is a type of fastener characterized by a helical ridge known as thread. Most screw rotate in clockwise manner but few rotate in anticlockwise manner.

Use

It allows drilling into hard surfaces

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Inclined plane

An inclined plane is a flat supporting surface tilted at an angle, with one end higher than the other, used as an aid for raising or lowering a load. The inclined plane is often used to lift a load over a vertical obstacle.

Importance of Simple Machine

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• Simple helps man to overcome friction in doing work.

• It helps to move load over a long distance.

• It helps to save time and effort

• It is more efficient.
• Simple machines are basic and simple to operate.

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GENERAL EVALUATION\REVISIONAL QUESTIONS

1. What is a machine?
2. Categorize the following to the class of lever they belong to: fore arm, plier, nutcracker, fishing rod.
3. State five effect of radiation.
4. State four reasons for abortion.
5. What is nuclear transmutation?

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READING ASSIGNMENT

Basis Science Made Easy for JSS Three by F.I Kehinde et al. Chapter 17. Pg 70-82.

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WEEKEND ASSIGNMENT

1. An example of a first order lever is � (a) fore arm� (b) nutcracker� (c) seesaw� (d) pulley
2. The principle of inclined plane is used in the construction of which of the following� (a) pulley� (b) staircase� (c) lift� (d) crane
3. ___ has the load between the fulcrum and effort� (a) First Order lever� (b) Second Order Lever� (c) Third Order Lever� (d) Wedge
4. Which of the following radiation has the lowest penetrating power?(a) alpha rays� (b) beta rays� (c) gamma rays� (d) X-ray
5. The clear outer layer of the eye is� (a) iris� (b) cornea (c) retina� (d) lens

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THEORY

1. Explain the three types of lever giving an example for each.
2. State the importance of machine.

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