MOTION AND MEASUREMENT OF DISTANCES
In ancient times, measurements were often based on the human body. For example, the length of a foot, the width of a finger, and the distance of a step were commonly used units. In ancient Egypt, the length from the elbow to the fingertips, known as a cubit, was a standard unit of length. Similarly, various cultures used body parts as units of measurement, but these varied from region to region, leading to inconsistencies.
The need for standardized measurements became evident to avoid confusion and ensure accuracy. In 1790, the French developed the metric system, which provided a uniform set of measurements. Today, scientists worldwide use the International System of Units (SI units) for consistency.
The SI unit of length is the metre (m). A metre is divided into 100 equal parts called centimetres (cm), and each centimetre is further divided into 10 millimetres (mm). For larger distances, the kilometre (km) is used, where 1 km equals 1000 metres.
Various tools are used to measure length, depending on the object's size and shape. For example, a tailor uses a tape measure, while a cloth merchant might use a metre rod. For smaller measurements, such as the length of a pencil, a 15 cm scale from a geometry box is appropriate.
Motion refers to the change in the position of an object over time. Different types of motion can be observed in our daily lives and the natural world. The main types of motion are: