3. The standard unit of measuring is second and
written as ‘s’. The larger units of time are minutes
and hours, written as ‘min’ and ‘h’.
Some units and conversionsare as follows:
60 seconds = 1 minute
60 minutes = 1 hour
24 hours = 1 day
30 days = 1 month
12 months = 1 year
10 years = 1 decade

4. • An object is said to be in motion when its
position changes with time or with
respect to its surrounding .
• Types of motion
Rectilinear motion
Circular motion
Rotational motion
Periodicmotion

5. • An object which takes longer time to cover a
certain distance is said to be slow motion.
• An object which takes a shorter time to cover the
same distance is said to be fast motion .
• Even the same object may move fast at one time .
A bus may move slowly on busy road and faster on
an empty road . We can find out wether an object
is slow or fast by knowing its speed.

6. • Speed of a moving object is the distance
travelled by it in a unit time.
• We can calculate the speed of the object
by using the formula :
Speed = Distance travelled
Time taken

7. Uniform motion
An object moving along a straight line path is said
to have a uniform motion if its speed remains
constant.
Non – uniform motion
 An object moving along a straight line path is said
to have anon-uniform motion when its speed keep
changing (i.e.,it does not remain constant).