7. Experiments with Water
What floats – what sinks?
Ayesha was waiting for dinner. Today Ammi was making her
favourite food – puri and spicy potatoes.
Ayesha watched as her mother rolled out the puri and put
it in the hot oil. She saw that at first the puri sank to the
bottom of the pan. As it puffed up, the puri came up and
started floating on the oil. One puri did not puff up and did
not float like the others. On seeing this, Ayesha took some
dough and rolled it into a ball. She flattened it and put it in
a bowl of water. Alas! it sank to the bottom and stayed there.
Think what would happen if
Š Ayesha put a puffed puri in a bowl of water. Would
it sink or float?
Š You put a steel plate on water. Would it sink or
float? What would happen to a spoon?
Š Would the cap of a plastic bottle sink
or float on water?
In the evening Ayesha went for
a bath. She had just come out
when her mother called, “Ayesha,
you have dropped the soap in the
water again. Take it out and put it
in the soap case.” Ayesha was in a
hurry and the soap case fell out of
60
Looking Around
her hands. It started floating on water. Ayesha
gently put the soap in the soap case. She saw
that the case continued to float, even with the
soap in it.
Have you seen that some thing float on
water while others sink? Think how this
happens! The poem here raises such
questions.
Why, Oh Why?
A wooden boat
in water will float.
But a needle will sink!
Why does this happen?
Let me think...
An iron ship
will also float,
though its’ much heavier
than my boat!
But a needle,
light as a leaf,
thin as a pin,
will sink right in!
Why does this happen?
Let me think...
– Shishir Shobhan Ashthana
Chakmak, December 1985
(Translated by Anupa Lal)
Do this and find out
Do this experiment in groups of four friends. Each group
will need a big pot filled with water and the things
listed in the table. Put each thing one-by-one in water
and observe. Write your observations in the table given
on the next page.
Experiments with Water
61
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