Science [1 Marks Each] QUE - ANS

The motion in a straight line is called rectilinear motion. For example, motion of a bullet fired from gun and motion of a stone falling down from a height.

It is important to know how far a place is, so that we can have an idea how we are going to reach that place, i.e., by walking, taking a bus or train, a ship, an aeroplane or even a spacecraft.

Rest: The object which do not change their positions with the time are said to be at rest. Motion: The object which change their position with time are said to be in motion.

The motion which repeats after a regular interval of time is called periodic motion.

Movement of an object along a circular path is called circular motion. Direction of moving body always changes in circular motion. For example, the moon moves around the earth.

Our classroom is said to be at rest according to the definition of motion.

The hour hand of the wall clock is in motion because it is changing its position.

Thread

Very small length like thickness of coin or wire is expressed in millimetres (mm).

Kilometre (km).

Millimetre (mm).

Measuring tape is suitable to measure the girth of a tree.

Magnitude and unit are the two parts which must be mentioned to state the results of a measurement.

A quantity adopted as a standard of measurement of a physical quantity is called unit.

Measurement is the technique developed for correct judgement of dimensions of various objects.

To guess the dimensions of an object without actual measuring is known as estimation. It is difficult to make near about correct estimate. It needs a lot of experience.

Animals were used to pull vehicles in ancient times.

Steam engine