Jouman Bibi Nousrat

Energy

Learning objectives At the end of the lesson, you should be able to:1. Recall the definition for energy and state its unit.2. Iist the different forms of energy and their sources.3. Perform simple calculations for kinetic (K.E = ½

mv2 ) and potential energy( P.E = mgh) using the formulae.

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Prior knowledge

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Different forms of energy

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ENERGY

Electrical Energy

Heat Energy

Light Energy

Kinetic (Motion) Energy

Sound Energy

Chemical Energy

Potential Energy

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memonicHe Keeps Eating Lightly

Salted Potato ChipsHeat Kinetic ElectricalLight Sound Potential

Chemical 9

Worksheet

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1. (a) What do you understand by energy? State its unit.

(b) Energy can be classified into two groups; namely stored energy and ………….. .

2. (a) Light energy is produced by luminous bodies like the sun,................, and

…………….

(b) …………., ………….. And batteries are sources of chemical energy.

(c) …………….. Energy can be produced by generators, cells or batteries. It is a form

of energy that can be converted from one form to another.

(d) …………….. Is produced by vibrating objects.

(e) A hot bowl of soup possesses ……………… energy.

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3. Match the following source of energy with the forms of energy obtained from them.

Sources forms

SunGravitational potential

Fossil fuel Chemical

A boy running Solar

A cyclist on the top of a hill Kinetic12

Calculations for kinetic and potential energy

1.A stone of mass 20 kg is released from a height of 5 m above the ground. Calculate the gravitational potential energy of the stone at the point of release. Take g = 10 m/s2.

2.From the Form 3 textbook pg 76 no 1:

Calculate the kinetic energy of a body of mass 10 kg moving at 5 m/s.

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Law of conservation of energyEnergy can neither be created nor destroyed. Energy can be transformed from one form to the other.

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Energy Transfer

Energy Form =

Where to Where? icehands

HEAT

Energy Transfer

Energy Form =

Where to Where? appliance

(TV, computer, etc)

outlet

ELECTRICAL

Energy Transfer

Energy Form =

Where to Where?

CHEMICAL

Fly(food)

Frog(growth)

Energy Can Be TransformedElectrical energy is transferred from the wall socket to the computer.Electrical energy is transformed to sound and light energy when the computer is turned on.Electrical energy is transformed to heat energy when the computer stays on.

Summary of the lessonEnergy

Forms of energy

Formulae for Kinetic energy and Potential energy

Law of conservation of energy.

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