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NCERT Solutions for Class 5th The World Around Us Chapter 7 Water Wheel — Activity 8

Book page 124 Updated on2026-09-19

Q1.
Water Wheel — 1. Take an empty paper cup and five spoons. 2. Make five holes around the cup and insert the spoons. 3. Then, insert a pencil or straw through the bottom of the cup. 4. Observe that the cup moves around the pencil like a wheel. 5. Balance your wheel on a container as shown in the image.
The paper-cup water wheel balanced on a container, as pictured on page 124.
Answer

How to build it:

  1. Take an empty paper cup — a used tea cup is fine. Wipe it dry.
  2. Make five small slits round the side of the cup, all at the same height and equally spaced, so they sit like the numbers on a clock face.
  3. Push one plastic spoon into each slit, with the bowl of the spoon facing outwards and all five facing the same way round. Fix them with a little tape if they wobble.
  4. Make a small hole in the centre of the bottom of the cup and push a pencil or a straw straight through it, so the pencil is the axle.
  5. Spin the cup gently with your hand. Check that it turns freely round the pencil like a wheel. If it sticks, make the hole slightly bigger.
  6. Rest the two ends of the pencil on the rim of a bucket or a tub, or on two tall glasses, so the cup hangs in the air and can turn.
Pencil (axle) Pour water here Wheel turns Rest the pencil across a bucket so the cup can spinfreely.
A paper cup with five spoons round it, spinning on a pencil — a home-made water wheel.

What you observe at step 4: the cup does turn freely around the pencil, exactly like a wheel on an axle. That is the test that your wheel is ready.

Do it over a bucket or outside. There will be splashes. And use a straw rather than a pencil if the cup is small — it is lighter, so the wheel turns more easily.
Q2.
6. Now, pour water onto your wheel. 7. Does the water make the wheel move?
Answer

Yes. The moment the falling water hits the spoons, the wheel starts to turn. Pour a thin stream and it turns slowly. Pour a thicker, faster stream and it spins quickly. Stop pouring and the wheel slows and stops.

How to pour:

  1. Fill a mug or a bottle with water.
  2. Hold it above one side of the wheel — not over the middle.
  3. Pour a steady stream so it lands inside the bowls of the spoons.
  4. Watch the wheel. Then pour from higher up and watch again.
How I pourWhat the wheel does
A slow trickleTurns slowly, and sometimes stops
A steady streamTurns smoothly, round and round
From higher upTurns faster — the water arrives with a harder push
Over the centre of the wheelHardly turns; the push must land on the spoons at the side
Stop pouringSlows down and stops
Why it happens: Falling water has energy because it is moving. When it lands in the bowl of a spoon it pushes that spoon down. The next spoon comes round, gets pushed in its turn, and so the wheel keeps turning. The energy of the moving water has become the turning of the wheel. So flowing water is a source of energy.
The real thing: In hilly areas, watermills called gharaats use flowing water to grind grain — a big wooden wheel in a stream turns a grinding stone, with no fuel and no electricity. In a hydro power station, falling water spins a big wheel called a turbine, and that makes electricity for whole cities. Your paper cup works on the same idea.
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