Basic Science and Technology - Junior Secondary 2 - Calculation involving work done

Calculation involving work done

Get it on Google Play
Get it on the Apple App Store
  1. Home
  2. Comprehensive Lesson Plan and Notes
  3. Junior Secondary 2
  4. Calculation involving work done

TERM: 2ND TERM

WEEK: 2

CLASS: Junior Secondary School 2

AGE: 13 years

DURATION: 40 minutes each for 2 periods

DATE:

SUBJECT: Basic Science

TOPIC: Calculation involving work done

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

  1. ) Define “energy”, “power” and “workdone”, stating their formulas and SI units
  2. ) Perform calculations to determine workdone

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:

PRESENTATION

TEACHER’S ACTIVITY

PUPIL’S ACTIVITY

STEP 1

Review

The teacher revises the previous lesson.

Learners pay attention

STEP 2

Introduction

He defines energy, power and workdone. Stating their formulas and SI units

Learners pay attention and participate

STEP 3

Explanation

He then performs calculations to determine workdone

Learners pay attention and participate

STEP 4

NOTE TAKING

The teacher writes a short note on the board for the learners to copy

The learners copy the note from the board

 

NOTE

CALCULATION INVOLVING WORK DONE

Energy: Energy is the capacity to do work. It exists in various forms, such as kinetic, potential, thermal, electrical, etc.

    • Formula: Energy is measured in joules (J), and it depends on the type of energy being considered (e.g., KE= ½mv2 for kinetic energy).
    • SI Unit: The SI unit of energy is joule (J).

 

Power: Power is the rate at which work is done or energy is transferred. It measures how quickly energy is used or work is completed.

    • Formula: P=W/t =  where P is power, W is work done, and t is the time taken.
    • SI Unit: The SI unit of power is watt (W), where 1 watt = 1 joule per second (1 W = 1 J/s).

Work Done: Work done refers to the energy transferred when a force is applied to move an object over a distance.

    • Formula: W=F×d, where W is work done, F is the force applied, and d is the distance moved.
    • SI Unit: The SI unit of work is joule (J).

 

Calculations to Determine Work Done:

Example 1:

If a force of 10 N is applied to push an object over a distance of 5 meters, the work done can be calculated as:

W=F×d

=10 N×5 m

W =50 J

 

Example 2:

If a person lifts a 20 kg box vertically through a height of 3 meters, the work done against gravity can be calculated by considering the gravitational force acting on the box. The gravitational force is

F=m×g

=20 kg×9.8 m/s2

=196 N

.

Now, the work done is:

W=F×d

=196 N×3 m

W =588 J

 

EVALUATION:

  1. Define energy, power, and work done. State their formulas and SI units.
  2. Differentiate between potential energy and kinetic energy, giving appropriate examples.
  3. A person pushes a car with a force of 200 N for a distance of 10 meters. Calculate the work done by the person.
  4. A 50 kg object is lifted to a height of 4 meters. Calculate the work done to lift the object. Assume the gravitational acceleration is 9.8 m/s2.
  5. A machine does 500 J of work in 5 seconds. Calculate the power output of the machine.

CLASSWORK: As in evaluation

CONCLUSION: The teacher marks their books and commends them positively