Motion And Measurment Of Distances

When objects move along a straight line such motion is called rectilinear motion. A sprinter in 100m race move along a straight track. This is an example of rectilinear motion.

We cannot use an angul (finger) or mutthi (fist) as standard unit of measurement of length because the sizes of body parts of different people are different. So it can create confusion.

International system of units (SI Units) is the system of unit of measurement used all over the world now.SI unit for length is metre.

The height of a girl in cm is 150 cm and in mm is 1500 mm.

Motion of ceiling fan is circular motion and motion of a pendulum is periodic motion.

When an object moves in a circular path, such motion is called circular motion. For example- Motion of a point marked on the blade of an electric fan is a circular motion.

We can’t use elastic tape to measure distances because we will not know how much we stretched the tape during measurement. It will cause error.

An object repeats its motion after some time; this type of motion is called periodic motion. For example- Motion of a pendulum is a periodic motion.

10 mm, 5 cm,1 km

1000 m =1km.Therefore 3000 m = 3km.

The motion of a falling stone is rectilinear motion and motion of a stone tied to a tread and whirled with hand is circular motion.

200 cm and 2000 mm

We can measure the length of a curved line by using a thread. Measure the length between the beginning and final mark on the thread.

Height of Reena is 170 cm.

1 km, 1 m, 1 cm, 1 mm.

When objects move along a straight line such motion is called rectilinear motion. Whereas when an object moves in a circular path, such motion is called circular motion.

Units of length are kilometres, metres, centimetres, millimetres etc.

Kilogram is the unit of weight whereas a kilometre is unit of length.

1. circular
2. Periodic
3. 3000
4. Periodic.