SUBJECT: Basic Science and Technology

CLASS: JSS2

TERM: Second Term

WEEK: 3

TOPIC: Energy Transfer When Work is Done

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Instructional Materials

• Charts showing energy transfer
• Videos of energy transfer (e.g., a moving car, lifting an object)
• Textbooks and online resources
• Ball, inclined plane, spring balance

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Methods of Teaching

• Explanation
• Demonstration
• Discussion
• Problem-solving
• Question and answer

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Previous Knowledge

Students have been taught about Potential and Kinetic Energy in their previous lessons.

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Behavioral Objectives

By the end of the lesson, students should be able to:

1. Define work in relation to energy transfer.
2. Explain the concept of energy transfer when work is done.
3. State the relationship between work and energy.
4. Solve simple problems related to work and energy transfer.

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Keywords

• Work – The force applied to an object to cause displacement.
• Energy Transfer – Movement of energy from one object to another.
• Kinetic Energy – Energy possessed by a moving object.
• Potential Energy – Stored energy in an object.
• Joule (J) – Unit of measurement for work and energy.

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Set Induction (Introduction)

The teacher asks students:

• Have you ever pushed a heavy object?
• How do you feel after running a long distance?
• What happens when you lift an object from the ground?

The teacher then explains that energy is transferred when work is done on an object, leading to movement or change in form.

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Lesson Content

Sub-topic 1: Meaning of Work and Energy Transfer

Work is the application of force on an object to cause displacement. It is done when energy is transferred from one object to another.

Formula for Work Done

Work Done = Force × Distance

Where:

• Work is measured in Joules (J)
• Force is measured in Newtons (N)
• Distance is measured in meters (m)

Examples of Work Done in Daily Life

• Pushing a car
• Lifting a bag
• Kicking a football
• A moving bicycle

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Sub-topic 2: Relationship Between Work and Energy

• Work and energy are measured in Joules (J).
• Energy is the ability to do work.
• When an object is lifted, potential energy is converted into kinetic energy when released.
• The Work-Energy Principle states that the change in an object’s kinetic energy equals the net work done on it.

Examples of Energy Transfer in Work Done

1. A moving car – The engine transfers energy to the wheels, causing movement.
2. Throwing a ball – Energy from your hand is transferred to the ball.
3. A swinging pendulum – Converts kinetic energy to potential energy and vice versa.

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Sub-topic 3: Calculation of Work Done

Example 1

A force of 20N pushes an object 5 meters. How much work is done?

Work Done = 20N × 5m = 100J

Example 2

An object moves 8 meters when 5000J of work is done. Calculate the force applied.

Force = Work Done ÷ Distance
Force = 5000J ÷ 8m
Force = 625N

Example 3

A 2kg book is lifted 0.75 meters. Calculate the work done.

Work Done = Mass × Gravity × Height

Gravity = 10m/s²

Work Done = 2kg × 10m/s² × 0.75m
Work Done = 15J

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Evaluation (Fill in the Blanks)

1. Work is done when ______ is applied to an object to cause displacement.
   a) Mass
   b) Force
   c) Pressure
   d) Power
2. Work done is measured in ______.
   a) Newtons
   b) Meters
   c) Joules
   d) Watts
3. When an object falls, ______ energy is converted into ______ energy.
   a) Electrical, chemical
   b) Kinetic, potential
   c) Potential, kinetic
   d) Chemical, sound
4. The work done when a force of 30N moves an object 4m is ______ J.
   a) 60
   b) 120
   c) 150
   d) 200
5. Energy is the ______ to do work.
   a) Ability
   b) Force
   c) Object
   d) Displacement

Answers: 1(b), 2(c), 3(c), 4(b), 5(a)

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Class Activity Discussion (FAQs)

1. What is work in physics?
   Work is the application of force to move an object.
2. What is energy transfer?
   It is the movement of energy from one object to another.
3. How is work related to energy?
   Work is done when energy is transferred to an object.
4. What happens when no movement occurs after applying force?
   No work is done.
5. How does friction affect work?
   Friction opposes movement, reducing work efficiency.
6. What is the SI unit of work and energy?
   Joule (J).
7. What are examples of energy transfer?
   • Electrical energy → Light energy (bulb)
   • Chemical energy → Mechanical energy (car engine)
8. How do machines help in doing work?
   Machines reduce the force needed to do work.
9. How do plants get energy?
   From the Sun through photosynthesis.
10. What is the Work-Energy Principle?
    It states that the change in kinetic energy equals the work done.

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Presentation Steps

1. Step 1: The teacher revises the previous topic.
2. Step 2: The teacher introduces the new topic using simple examples.
3. Step 3: The teacher explains how energy transfer occurs when work is done.
4. Step 4: The teacher solves examples on work done.
5. Step 5: The teacher allows students to ask questions and discuss.
6. Step 6: The teacher guides students in solving more work-energy problems.

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Assessment (Short Answer Questions)

1. Define work.
2. State the formula for calculating work done.
3. How is energy transferred when work is done?
4. If a force of 15N moves an object 10m, calculate the work done.
5. What are two examples of energy transfer in work done?
6. State the Work-Energy Principle.
7. What happens when an object is pushed, but does not move?
8. Explain the relationship between work and kinetic energy.
9. Calculate the work done in lifting a 5kg box 2m high.
10. Name three situations where work is done in daily life.

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Conclusion

The teacher marks students’ work, provides corrections, and summarizes the lesson.