Page 242 - New Medley 4 Semester 2 PDF (Merged)

Activity

Take a ball and throw it up. What happens after some time?

The atmosphere is held around the Earth due to gravity. Our

earth is revolving around the sun on a fixed path. This is due
to gravitational force between the Earth and the sun. Have you

ever wondered why the water from the oceans does not spill out
in space? This is also because of the gravitational force applied

by the Earth on the ocean water.

Roll a ball on the ground and observe it. How long does it
keep rolling?

The ball slows down and stops moving after some time. This

is due to a force called friction acting between the ball and
the ground. The force of friction acts on all moving objects.

WORK

When we push or pull a table or a chair by

applying force, it moves through a distance.
It means we have done the work.

Now, push a heavy cupboard or almirah with

alomst equal force. It did not move because
the force applied was not enough. Hence,

no work was done. To get the work done in
this case, we need to apply more force which is possible if we have more energy.

ENERGY

What is energy?

Energy is the ability to do work. We need energy
to do different types of work.

Sources of energy

Everything, whether living or nonliving, needs
energy to do work. Nonliving things such as

car, bus, fan, etc. get energy from petrol and Energy is used to do different
types of work

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