10. Motion and Measurement of Distances

 There are various modes of transport that are used to go from one place to another.

 The ancient people use hand-span, foot-span, finger width, palm length, the distance of

a step, etc. as units of measurements.

 The measurement of a quantity is expressed in two parts. One part is a number. The

other part is the unit of measurement.

 Nowadays, the International system of units (SI) is used as standard units all over

the world.

 Metre (m) is the SI unit of length.

 1 m 100 cm 1000 mm   and

1

1 m km

1000



 In our daily life we use various types of measuring devices such as metre scale,

measuring tape, metre rod etc.

 The length of a curved line can be measured with the help of a thread. Measurement

of the thread on a metre scale gives the length of the curved line.

Objects are either at rest or in motion.

 Types of motion:

 When an object moves along a straight line, it possesses rectilinear motion.

 When the distance of the object from a fixed point remains constant, it possesses

circular motion.

 When an object moves to and fro about a fixed point, it possesses periodic

motion.

 Motion of an object is the change in its position with time.

 The fastness or slowness of the movement of an object is determined by measuring the

distance travelled with time.

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