Q1.
Identify the appropriate units for measuring each of the following. (Height of India Gate — 42; Length of a handkerchief — 40; Depth of a well — 50; Length of a mobile phone — 13; Length of an elephant's trunk — 2; Distance between two buttons on a shirt — 5)
Answer
Big things get metres (m). Small things get centimetres (cm). Here is the filled table.
| Quantity | Number given | Unit | Why |
|---|---|---|---|
| Height of India Gate | 42 | metre (m) | It is a huge gate — much taller than your school |
| Length of a handkerchief | 40 | centimetre (cm) | It fits in your pocket |
| Depth of a well | 50 | metre (m) | A well goes deep down into the ground |
| Length of a mobile phone | 13 | centimetre (cm) | It fits in your hand |
| Length of an elephant's trunk | 2 | metre (m) | A trunk is longer than you are tall |
| Distance between two buttons on a shirt | 5 | centimetre (cm) | It is only about a finger's width |
Here is a quick way to decide.
- Picture the thing. Close your eyes and see it.
- Ask: can I hold it? If yes, use centimetres.
- Ask: is it as tall as a room, a tree or a building? If yes, use metres.
- Check by trying the other unit. If the answer sounds silly, you picked wrong.
Why the check works: Try 42 cm for India Gate. That is shorter than your school bag — India Gate cannot be that small. Now try 40 m for a handkerchief. That is longer than four buses in a line — no handkerchief is that big. The silly answer tells you the unit is wrong.
Did you know? India Gate in New Delhi really is about 42 m tall. It was built to remember Indian soldiers, and their names are carved on its walls.