Page 14 - Understanding NCERT Science 09
P. 14
Particles of matter are continuously • If we consider each student as a
moving, that is, they possess what we call particle of matter, then in which group
the kinetic energy. As the temperature rises, the particles held each other with the
maximum force?
particles move faster. So, we can say that with
increase in temperature the kinetic energy of
the particles also increases. Activity ______________ 1.7
In the above three activities we observe
• Take an iron nail, a piece of chalk and
that particles of matter intermix on their own
a rubber band.
with each other. They do so by getting into • Try breaking them by hammering,
the spaces between the particles. This cutting or stretching.
intermixing of particles of two different types • In which of the above three
of matter on their own is called diffusion. We substances do you think the particles
also observe that on heating, diffusion are held together with greater force?
becomes faster. Why does this happen?
Activity ______________ 1.8
1.2.3 PARTICLES OF MATTER ATTRACT
• Take some water in a container, try
EACH OTHER
cutting the surface of water with your
fingers.
Activity ______________ 1.6 • Were you able to cut the surface of
water?
• Play this game in the field— make four • What could be the reason behind the
groups and form human chains as surface of water remaining together?
suggested:
The above three activities (1.6, 1.7 and 1.8)
• The first group should hold each
other from the back and lock arms suggest that particles of matter have force
like Idu-Mishmi dancers (Fig. 1.3). acting between them. This force keeps the
particles together. The strength of this force of
attraction varies from one kind of matter to
another.
Q 1. Which of the following are
uestions
matter?
Chair, air, love, smell, hate,
almonds, thought, cold, lemon
water, smell of perfume.
2. Give reasons for the following
Fig. 1.3
observation:
The smell of hot sizzling food
• The second group should hold hands
to form a human chain. reaches you several metres
• The third group should form a chain away, but to get the smell from
by touching each other with only their cold food you have to go close.
finger tips. 3. A diver is able to cut through
• Now, the fourth group of students water in a swimming pool. Which
should run around and try to break the property of matter does this
three human chains one by one into observation show?
as many small groups as possible.
• Which group was the easiest to break? 4. What are the characteristics of
Why? the particles of matter?
MATTER IN OUR SURROUNDINGS 3
Rationalised 2023-24
