11 – Work and Energy
Q. 1. Fill in the blanks with the appropriate term from the
brackets:
(1) A bucketful of water is to be
drawn from a well……………. will be done when a ………… is applied to do this, because
there will be a ………….. of water.
(displacement, work, force)
(2) If a ball is dropped on the
sloping roof of a house, it acquires …………….. and falls
on the ground. That is, transformation of……………… energy into
……..energy takes
place. (kinetic, potential, motion)
(3) You might have seen some
beautiful fireworks during Diwali. It is an example of
transformation of ……………… energy into ……..energy. (light, atomic, chemical,
solar)
(4) The solar cooker
is an application of the ……………… energy of the sun, while solar cells, solar
lamps are application of the………….. energy of
the sun. (light, chemical, heat)
(5) 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………… work will be done.
(equal. more, less)
(6) The capacity that an object has for doing work is called……………
(energy, displacement force)
Ans. (1) A bucketful of
bucketful of water is to be drawn from a well, work will be
done when a force applied to do this, because there will be a displacement of
water.
(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.
(3). You might have seen some beautiful fireworks during
Diwall. It is an example
transformation of chemical energy into light energy.
(4) 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.
(5) 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.
(6) The capacity that
an object has for doing work is called energy .
Q. 2. Match the
pairs :
Ans (1)
Rolling object - Kinetic energy
(2) Food- Chemical energy
(3) Stretched bow - Potential energy
(4) Sunlight - Heat energy
(5) Uranium – Atomic energy
Q. 3. Find the odd one out :
(1) Diesel, crude oil, natural gas, wind.
(2) A running car, hauling a log, a book kept on a table,
picking up the school bag.
(3) Sunlight, wind, waves, petrol.
(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. (1) Wind (Others are non-renewable fossil fuels).
(2) A book kept on
the table. (Others are showing displacement and thus possess
kinetic energy)
(3) Petrol (Others are renewable energy resources)
(4) Putting off the light when going out. ( this is the only
way to save energy, others are actions of wasting energy)
Q. 5. Can you
tell ?
(1) When can we say that displacement has taken place?
Ans. When the position of any object changes, than we can
say that displacement has taken place.
(2) What should be taken into account for measuring work?
Ans. For measuring
work, both the force and the displacement must be considered
(3) What are the
various forms of energy?
Mechanical energy, heat energy, light energy,
sound energy. chemical energy and electrical
energy are the various forms of energy.
(4) Describe natural chain of
transformation of energy.
Ans Plants prepare food by utilizing solar energy. The food
produced is in the form 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:
Muscular energy
Solar energy Chemical energy Heat energy
(5) 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.
(6) 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.
7) 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 the oceanic waves.
(8) 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.
(9)Why should we maximize the used of non-conventional
energy resources.
The non-conventional energy resources are renewable energy
resources. They are inexhaustible and continuously available resources. On the
other hand, the traditional nonrenewable 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 maximize the use of non-conventional energy resources.
