Basic Science and Technology - Junior Secondary 2 - Energy transfer when work is done

TERM: 2^ND TERM

WEEK: 3

CLASS: Junior Secondary School 2

AGE: 13 years

DURATION: 40 minutes each for 2 periods

DATE:

SUBJECT: Basic Science

TOPIC: Energy transfer when work is done

SPECIFIC OBJECTIVES: At the end of the lesson, the learners should be able to

1. ) Illustrate how energy transfer occurs when work is done
2. ) Discuss the interchangeability of work and energy

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, story-telling, videos from source

INSTRUCTIONAL MATERIALS: Recommended Basic Science textbooks for Junior Secondary School 2

INSTRUCTIONAL PROCEDURES: PERIOD 1-2:

NOTE

ENERGY TRANSFER WHEN WORK IS DONE

Illustration of Energy Transfer When Work is Done:

When work is done, energy is transferred from one object or system to another. This transfer can happen in various forms, such as mechanical, thermal, or electrical energy. Here’s a simplified illustration:

Example: Lifting a Book

• When you lift a book from the ground to a shelf, you apply a force over a distance. The force you exert on the book causes it to move against the pull of gravity.
• The work done in lifting the book is transferred to the book as gravitational potential energy. The higher the book is lifted, the more energy is transferred to it.

Formula for Work Done:

W=F×d

where:

• W is the work done (in joules),
• F is the force applied (in newtons),
• d is the distance the object is moved (in meters).
• As energy is transferred to the book, the work done on the book equals the energy stored as its potential energy.

Energy Transfer:

• The chemical energy in your muscles (from food) is converted to mechanical energy to lift the book.
• This mechanical energy is transferred to the book as potential energy due to its height above the ground.

Interchangeability of Work and Energy:

Work and energy are closely related concepts in physics, and they can be considered interchangeable because:

• Work is defined as the process of transferring energy to or from a system. When work is done on an object, energy is transferred to it or from it.
• Energy is the capacity to do work. Energy exists in various forms, such as kinetic energy (energy of motion), potential energy (energy due to position), thermal energy (heat), and more.

Key Points:

• Work and Energy Transfer: Work done on an object results in a change in its energy. For example, when you push a car, the work you do transfers energy to the car, causing it to move (kinetic energy).
• Energy Conversion: Energy can be converted from one form to another. For example, when you turn on a light bulb, electrical energy is converted to light and thermal energy.
• Work as Energy Transfer: When work is done (e.g., lifting an object), the energy required to perform that work is transferred to the object. This transfer of energy is what causes a change in the object's state, whether it's in motion or positioned higher (potential energy).

In essence, work is the process of transferring energy, and energy is the ability to do work. They are directly related and often used interchangeably in physics to describe the movement and transformation of energy.

EVALUATION:

1. What is the relationship between work and energy? Explain how work is used to transfer energy.
2. Provide an example where energy is transferred when work is done. How does this transfer happen in the example?
3. Using the formula for work, calculate the work done when a person applies a force of 15 N to move an object 10 meters.
4. Explain how energy can be converted from one form to another when work is done. Provide examples of different types of energy conversions.
5. How is kinetic energy related to work? Can work be done without changing the kinetic energy of an object? Justify your answer

CLASSWORK: As in evaluation

CONCLUSION: The teacher marks their books and commends them positively