Page 66 - Science Class 06
P. 66
TIME-PATTERN
In view of me-pa ern, a change may occur
a er regular intervals of me or at irregular
ones, i.e., at random. So, in terms of me-
pa ern, changes are of two kinds—periodic
and non-periodic. Evidently, periodic
changes can be predicted while non-
periodic ones cannot be predicted at all.
Lightning may occur any me, so it is
Periodic Changes
a non-periodic change.
These are the changes that keep happening PERMANENCY
at certain intervals of me. Time is the
biggest example of it. Everyday we get In view of permanency, a change may be ever
twenty-four hours and a er the periodic las ng or mely, i.e., for the me being only.
interval, the me on the clock is repeated So, in terms of permanency, changes are of
again. Another example of this can be that two types— permanent and temporary.
of weather. They keep coming a er a Permanent Changes
certain interval of me.
A permanent change is a change that lasts
for a longer me and are not reversible.
Examples : Burning of paper into black ash,
cooking of food, diges on of food into
blood, change of milk into curd, ripening of
fruits, etc.
Paper Burning of Paper Ash of Paper
Changes in the shape of the moon
are periodic changes. On burning paper, it turns into ash which cannot be
Non-periodic Changes turned back into paper. So, it is a permanent
The changes that occur once are non- Temporary Changes
periodic changes. Unlike periodic changes
Temporary changes are the changes which
that have a set me of coming and going,
are there only for a short period of me.
non-periodic changes have no such set
Generally, temporary changes are reversible.
me. For instance, a random rainy day
during summers may be considered a non- Examples : Squeezing of an inflated balloon,
periodic change. It changes the weather for stretching of a spring, mel ng of ice into
a day, but it is not a periodic change. water, cold milk to hot milk, etc.
66 Science-6
