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NCERT Solutions for Class 5th The World Around Us Chapter 4 Dripping Water — Activity 4

Book page 64 Updated on2026-09-19

Q1.
Look out for a dripping tap or poke a small hole in a used water bottle filled with water. Now, let the water drip. Collect the dripping water in a glass and carefully measure the time it took for the glass to fill up. Time taken to fill one glass: __________
Answer

What you will find: an ordinary slow drip fills a 200 ml glass in about 5 to 10 minutes. It looks like nothing is happening, and yet the glass fills.

How to do it

  1. Find a tap that drips even when it is closed tight. If you cannot find one, take an empty plastic bottle, fill it with water, and make one pin-hole near the bottom.
  2. Hold the bottle upright over a glass, or put the glass under the dripping tap.
  3. Note the time on a clock the moment the first drop falls. Write it down.
  4. Do not stand and watch — go and do something else, and come back to check.
  5. Note the time again the moment the glass is full. The difference is your answer.
Our reading (sample)Value
Started at11:05 a.m.
Glass full at11:11 a.m.
Size of the glass200 ml
Time taken to fill one glass6 minutes

Your tap will not drip at exactly the same speed. Write down your own time — that is your reading. A fast drip may take 3 minutes; a very slow one may take 15.

Do it properly: use the same glass throughout, and fill it right to the top mark each time. Guessing the time spoils the whole calculation that comes next.
Q2.
How many glasses would become full in one day?
Answer

With our reading of 6 minutes per glass, that comes to 240 glasses in one day — about 48 litres of water, from one tap that was only dripping.

The working, step by step

1 glass takes 6 minutes
Glasses in 1 hour = 60 ÷ 6 = 10 glasses
Glasses in 1 day = 10 × 24 = 240 glasses
If 1 glass holds 200 ml, then
Water in 1 day = 240 × 200 ml = 48000 ml = 48 litres a day
Water in 1 month = 48 × 30 = 1440 litres — almost one and a half thousand litres
If one glass fills in…Glasses in a dayWater lost in a day (200 ml glass)
3 minutes48096 litres
6 minutes24048 litres
10 minutes144about 29 litres
15 minutes96about 19 litres

Now use your own time. Divide 60 by your minutes to get glasses per hour, then multiply by 24.

Why the number is so big: The drip does not stop. It goes on through the lunch break, through the night, on Sunday, in the holidays. One drop is tiny; but 24 hours is 1440 minutes, and tiny multiplied by 1440 becomes large. This is the whole lesson: small things repeated many times add up to something huge — which is true of waste, and equally true of saving.
Put it in a way people feel: 48 litres is about three buckets. Ask your class — would anyone deliberately pour three full buckets down the drain every single day? Nobody would. But a dripping tap does it silently, and nobody notices. One washer, worth a few rupees, stops it.
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