Term: 1^{st} Term
Week: 9
Class: Senior Secondary School 1
Age: 15 years
Duration: 40 minutes of 5 periods each
Date:
Subject: Physics
Topic: Work, Energy and Power
SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to
INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source
INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures
INSTRUCTIONAL PROCEDURES
PERIOD 12
PRESENTATION 
TEACHER’S ACTIVITY 
STUDENT’S ACTIVITY 
STEP 1 INTRODUCTION 
The teacher reviews the previous lesson on Pressure, Archimedes principles and upthrust 
Students pay attention 
STEP 2 EXPLANATION 
He discusses the concept of work and energy

Students pay attention and participates 
STEP 3 DEMONSTRATION 
He discusses the concept of power

Students pay attention and participate 
STEP 4 NOTE TAKING 
The teacher writes a summarized note on the board 
The students copy the note in their books 
NOTE
WORK, ENERGY AND POWER
WORK
Work is defined as the product of force and distance in the direction of the force. It is a scalar quantity & measured in Joules.
Mathematically:
W = F X d 1.
W = mgh 2.
If a force is applied on a body at an angle Ø to the horizontal
Work done = FcosØ x d 3.
Work done to raise the body to an appreciable height
= FsinØ x d 4.
Example
A boy of mass 50kg runs up a set of steps of total height 3.0m. Find the work done against gravity
Solution
m = 50kg, h = 3m, g = 10m/s^{2}
Work done = m x g x h
= 50 x 10 x 3
= 1500 Joules
ENERGY
Energy is defined as the ability to do work. It is a scalar quantity &measured in Joules. There are many forms of energy. These include:
POTENTIAL AND KINETIC ENERGY
Potential Energy  is simply “stored energy” i.e. energy possessed by a body by virtue of its states:
P.E = mgh 5.
Kinetic Energy: is the energy possessed by a body by virtue of its motion. Examples area student running a race, wind or air motion, electrical charges in motion, a moving bullet
K.E = ½ mv^{2 }6.
Example I –
An object of mass 5kg is moving at a constant velocity of 15m/s.
Calculate its kinetic energy.
Solution
K.E = ½ mv^{2}
= ½ x 5 x 15 x 15
= 562.5 J
Example II
Find the potential energy of a boy of mass 10kg standing on a building floor 10m above the ground level. g = 10m/s^{2}
Solution:
P.E =m x g x h
= 10 x 10 x10
=1000 J
POWER
Power is defined as the rate of doing work or the rate of transfer of energy. It is a scalar quantity & measured in watt
Power = work done
Time 7
P = (F X d)/t = F X d/t = FV 8
Example A boy of mass 10kg climbs up 10 steps each of height 0.2m in 20 seconds. Calculate the power of the boy.
Solution
Height climbed = 10 x 0.2 = 2m
Work done = m x g x h = 10 x 10 x 2= 200 Joules
Power = work
Time
= 10 x 10 x 2
20
= 10watts
EVALUATION: 1. Define these terms
(i) power
(ii) work done
(iii) energy
4(a) State the law of conservation of energy.
(b) A body is displaced through a certain distance x by a force of 30N. If the work done is 100J and the displacement is in the direction of force, what is the value of x?
CLASSWORK: As in evaluation
CONCLUSION: The teacher commends the students positively