Ch.11: Work and Energy

Work and Energy | Class 6 | Science | Chapter 11 | Maharashtra State Board

In this video, we will delve into the fascinating world of work and energy and explore their relationship. We will begin by defining and distinguishing between different forms of energy, including mechanical, potential, kinetic, heat, light, sound, and chemical energy. Next, we will examine how energy is transformed from one source to another, and highlight the importance of energy conservation. We will also discuss the two main categories of energy resources, namely conventional (non-renewable) and non-conventional (renewable) energy resources. Specifically, we will focus on non-conventional energy resources such as solar, wind, tidal, hydroelectric/hydel power, energy obtained from oceanic waves, and atomic energy. By the end of this lesson, you will gain a better understanding of the different forms of energy and how they impact our daily lives.

Questions & Answers

1. Fill in each blank with the appropriate term from the brackets.

1. A bucketful of water is to be drawn from a well work will be done when a force is applied to this, because there will be a displacement of water. (displacement, work, force)

2. If a ball is dropped on the sloping roof of a house, it acquires motion and falls on the ground. That is, transformation of potential energy into kinetic energy takes place. (kinetic, potential, motion)

3. You might have seen some beautiful fireworks during Diwali. It is an example of transformation of chemical energy into light energy. (light, atom, chemical, solar)

4. (d)The solar cooker is an application of the heat energy of the sun, while solar cells, solar lamps are applications of the light energy of the sun. (light, chemical, heat)

5. (e)One labourer carried four pans of road metal through a distance of 100 metres. If he carries two pans of road metal through a 200 metre distance equal work will be done. (equal, more, less)

6. (f)The capacity that an object has for doing work is called energy . (energy, displacement, force)

2. Match the pairs.

Group 'A'	Answer	Group 'B'
Rolling object	Kinetic energy	Heat energy
Food	Chemical energy	Atomic energy
Stretched bow	Potential energy	Kinetic energy
Sunlight	Heat energy	Potential energy
Uranium	Atomic energy	Chemical energy

3. Can you tell ?

(a) When can we say that displacement has taken place?

Ans. When the position of any object changes, then we can say that displacement has taken place.

(b) What should be taken into account for measuring work?

Ans. For measuring work, both the force and the displacement must be considered.

(c) What are the various forms of energy?

Ans. Mechanical energy, heat energy, light energy, sound energy, chemical energy and electrical energy are the various forms of energy.

(d) Describe one natural chain of transformation of energy.

Ans. Plants prepare food by utilizing solar energy. The food produced is in the form of chemical energy. This food is consumed by animals. They develop muscular energy. The digestion of food also produce heat energy in the body.

This natural chain of transformation of energy can be shown as follows:

(e) Why should we save energy?

Ans. Saving energy is the need of the hour. When we produce energy, we need fuel on a very large scale. The fuels are also depleting fast from the earth. By more consumption of energy, lots of carbon dioxide is produced. This leads to global warming and pollution. In order to conserve our environment, we must save energy.

(f) What is ‘green energy’?

Ans. The energy resources which do not emit smoke and carbon products are called green energy resources. The energy produced in this way is the green energy.

(g) What are the non-conventional energy resources?

Ans. The inexhaustible and continuously available energy resources which were not traditionally used previously are called non-conventional energy resources. e.g. solar energy, wind energy, tidal energy, hydel power, atomic energy, energy obtained from oceanic waves.

(h) Which forms of energy from the sun are used in solar energy devices?

Ans. In solar cooker, solar heater and solar dryer, the heat energy from the sun is used. While in solar lamps light energy from solar energy is used. In solar cells, solar energy is used to produce electricity.

(i) Why should we maximise the use of non-conventional energy resources?

Ans. The non-conventional energy resources are renewable energy resources. They are inexhaustible and continuously available resources. On the other hand, the traditional non-renewable energy resources such as fossil fuels are getting fast depleted. They also create pollution and problems like global warming and climate change when used in excess. In order to save our earth and environment, we must maximise the use of non-conventional energy resources.

4. Who is the odd-one-out?

(1) Diesel, crude oil, natural gas, wind.

Ans. Wind. (Others are non-renewable fossil fuels.)

(2) A running car, hauling a log, a book kept on a table, picking up the school bag.

Ans. A book kept on a table. (Others are showing displacement and thus process kinetic energy.)

(3) Sunlight, wind waves, petrol.

Ans. Petrol. (Others are renewable energy resources.)

(4) Leaving the fan on in a vacant room, leaving the TV on while working, using AC during winter, putting off the light when going out.

Ans. Putting off the light when going out. (This is the only way to save energy, others are actions of wasting energy.)

5. Find out the types of energy from the following puzzle.

Ans. Potential, kinetic, heat, sound, wind, solar.

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E X T R A

1. Fill in the blanks choosing correct alternative.

1. Energy obtained from tides in the sea is tidal energy. (wind, tidal, hydroelectric)

2. A brick falling from the fifth floor of a building possesses kinetic energy. (geothermal, wind, kinetic)

3. The heat liberated during the fission of atoms of heavy element such as uranium is used to generate electricity at atomic power station. (uranium, nitrogen, helium)

2. Name in the following.

(a) The most important source of all energy.

Ans. Sun.

(b) The Unit of energy.

Ans. Joule.

(c) The energy used for doing mechanical work.

Ans. Mechanical energy.

(d) The energy obtained from motion.

Ans. Kinetic energy.

(e) The energy obtained through chemical.

Ans. Chemical energy.

(f) The energy which is stored in an object due to a specific state or position.

Ans. Potential energy.

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