* Look at a meter scale carefully and answer the following:
* How many mm are there in a cm?
mm = 1 cm
* How many cm are there in a m?
mm = l m
* Complete the following:
• 7875 cm = 78 m 75 cm
• 1195 m = 1 km 195 m
• 15 cm 10 mm = 160 mm
• 45 km 33 m = 45033 m.
A Quick Look
* The comparison of an unknown quantity with some known quantity is known as measurement.
* All physical quantities have standard units for the sake of uniformity.
* Length, mass and time are some of the fundamental physical quantities.
* The SI units for
Length - metre
Mass - kilogram
Time - second
Volume - litre (or) cm3
* While using ruler, the accurate measurement can be arrived by avoiding three types of possible errors.
* Volume of solids, liquids and regular objects is measured by direct measurement.
* Volume of irregular objects can be measured by water displacement method.
* Electronic balance is an instrument to provide accurate measurement of mass correct up to milligram.