To change raw materials for human use, a tool is an implement. It is viewed as a hand extension that increases the hand’s speed, power, and precision, making it man’s ally in the struggle for existence.
A flexible tool for measuring length is a measuring tape. Materials including fibreglass, cotton, plastic, and metal ribbon or strip are used to make it. It is hence a type of flexible ruler also referred to as a tape measure. It is measured in inches and centimetres.
The law of gravity is used by the plumb bob or plumb line to determine what is plumb (that is, what is exactly vertical, or true). A string hanging with a weight at the bottom will be vertical and perpendicular to every level plane over which it passes, and you don’t need to be an expert in physics to realise this.