Changes Around Us | Term 2 Unit 3 | 7th Science - Periodic and non-periodic change | 7th Science : Term 2 Unit 3 : Changes Around Us
Chapter: 7th Science : Term 2 Unit 3 : Changes Around Us
Periodic and non-periodic change
Periodic and
non-periodic change
Depending on whether or not a change repeats
itself after a definite period of time, it can be classified as periodic change
or a non-periodic change.
Periodic
changes
Changes that repeat themselves after a definite
interval of time are called periodic changes.
Rotation and Revolution of earth, beating of the
heart, clock striking every hour, motion of the seconds-hand / minute-hand /
hour-hand of a clock are some examples of periodic changes.
Every year we observe that seasons changes. We go
from rains to winter and winter to summer and so on.
* What types of clothes are worn in winter?
* What are the clothes that we wear in summer?
If the winter season changes into summer, we
observe change in the texture type of clothes we wear. We wear woolen clothes
in winter and cotton clothes in summer. Similarly, we observe that the winter
season is cool and summer season is hot. In winter, duration of night is longer
than in summer. We take cold drinks in summer but prefer hot tea, coffee or
milk in winter. These changes that we observe show the change of seasons.
The seasons and changes in weather occur because
earth rotates on its fixed axis. Changing seasons are almost periodic in
nature.
Non-periodic
changes
Changes that do not repeat themselves after a
definite interval of time and occur randomly are called non-periodic changes. Eruption of a volcano, occurrence of an earthquake, a streak
of lighting flash across the sky during a thunderstorm, running of a batsman
between the wickets, movement of legs while dancing are a few examples of
non-periodic changes.
Related Topics