NCERT Summary: Motion & Measurement of Distance | Science Class 6 PDF Download

Transport

• It is a mechanism in which a thing is carried from one place to another.

Transport system evolution

• In the earlier times, land transport was done using animals or human backs, while, water transport was done on hollow wooden logs or simple wooden boats.
• After the invention of wheel, bullock carts, camel carts were developed.
• Transport then evolved in the 19th and 20th century to bus, trains, cars, and airplane, jets, steam and motor boats, etc.

Distance

• It is length of the space between two points or between two places is called distance.
• Example: If the two points are close by, the distance between them will be small otherwise if the two points are far off, then the distance between them will be large.

Length

• Length tells us how long an object is.
• Measurement is comparison on an unknown quantity with a known quantity. The known quantity is called Unit.
• Measurement consists of two parts, a number (quantity) and a unit.
• Depending upon the unit, the number changes.

Standard Units of Measurements

• Scientists all over the world have accepted a set of standard units for measurements. This system of units is called International System of Units (SI units).

Needs for standard units of measurement

• Units like foot, hand span, cubit, footstep etc., vary.
• They depend upon the size of an individual, hence such units cause confusion in measurements.
• Example: length-meter, time-second, mass- kilogram.

Rules for writing symbols of units

• Units are usually written in small letters
• It is not given in plural form
• It is not followed by a full stop unless it is at the end of the sentence.

Measuring Length of a Curved line

• Instead of straight scale using measuring tape for the measurement of curved line or surface.

Motion

• Any change in position with time can be termed as motion.
• A motion can be termed as slow or fast based on the distance it covers in a specific amount of time.
• The objects which are not moving are said to be at rest.

Classification of motion on the basis of the path they follow

1. Rectilinear Motion: Motion where objects move along a straight line.
   Examples: sprinters in race, falling stones etc.
2. Circular Motion: Motion where objects move along a circular path.
   Examples: rotation of earth.
3. Rotational Motion: A type of circular motion where an object spins on its own axis, it is called rotational motion.
   Example: rolling ball, spinning top etc.
4. Periodic Motion: Motion where the object repeats its motion after a fixed interval of time. Examples: motion of swing, pendulum etc.