Sprinklers and Fountains

JJ Harrison via Wikimedia Commons: https://creativecommons.org/licenses/by-sa/3.0/

For the last two weeks we have focused in understanding concepts such as "Why and how things work?". To kindle the curiosity of kids we started by sharing questions that they wonder about in the world of science. These were the following questions that some of them have

1. What happens if a star crashes on the Sun?.
2. What is inside a black hole?.
3.Do aliens exist?.
4. What causes lightning to happen?.
5. Why do we laugh when we get tickled?.

After our discussion about the answers to the above questions we moved on to focusing on our activity that was planned for the day. Since it is summer we thought about sprinklers being on everywhere near the gardens.

1.So, how does the sprinkler work?. What is the principle?.

2. Can we make our own sprinklers using basic things around?.

 Most garden sprinklers work with the centrifuge sprinkler system. In this the centrifugal force in the center ( middle) makes the water move up and spin too. To use this principle we tried different models.

Model Sprinkler

Materials

1. Straw - 1
2. Skewer -1
3. Cello tape -1
4. Scissors -1

Procedure

1. Take a straw and poke it in the middle with a skewer (otherwise called kebab stick)

2. Cut small slits in the  upper part of the straw .

3. Bend it as a triangle and tape it with a cello tape.

4. Make sure the holes of the straws are open while securing it with the skewer.

5. Your manual sprinkler is ready.

When we tried it, kids were amazed to see that how the skewer in the middle spins generating the centrifugal force which in turn makes the water move up the straw while  sprinkling the water. We then suggested that we should try with one more straw added to the same. More water sprinkles with one more straw and kids thoroughly enjoyed it .

Magic bottle sprinkler

Kids were told to open the bottle kept outside in the balcony. They were surprised to see that when they opened it water would flow and when  closed it there was no water leaking. Kids were able to guess that the atmospheric pressure was more outside than inside the bottle. So, when the air enters the bottle water is pushed (flows) and stops when it is closed.

Kids wanted to make it by themselves. For this we filled the bottle with water and turned it upside down. We then poked holes using pushpins and removed them too. 

You can now see how it works.

We also talked about fountains and decided to make a model fountain with few materials in hand.

Bottle Fountain 

Materials

1. Plastic bottle (1 L) -2

2. Nail or a bigger sewing needle

3. Straw

4. Adhesive putty

5. Food colouring (optional)

6. Balloon -2

 Procedure

1.  Half fill one of the bottles with water and blow up a balloon and put it around the mouth of the bottle and tell kids to observe if the balloon deflates or not.

 2.  In another bottle make a small hole  using a sharp nail about 10 cm up the side of the plastic bottle. The hole should be about the size of the straw's diameter. Ask an adult to help.

3.  Place the straw into this hole so it is half inside the bottle and half out. Angle it so the outside end points upwards.

4.  Press adhesive putty around the straw on the outside of the bottle to reduce leakage from the hole.

5.  Fill the bottle halfway with water and add a drop of food colouring.

6.  Does the water come out the straw?...no, right?

7. Now, blow up the balloon. Keep the air inside the balloon while you stretch the balloon ends over the top of the bottle.

8.  Hold the balloon in place, then release the air into the bottle. Watch what happens as the balloon deflates.

9. Do this activity somewhere you can make a watery mess, such as a sink or outside.

 

What's happening?

 All around us, everything on Earth is being squeezed by the atmosphere above. Air pressure pushes equally in all directions, and is pushing on you. Same  is happening inside your fountain. The water in the bottle is squeezed by the amount of water on top of it. The same happens with the water in the straw.

The balloon on top of the water bottle without the hole stays the same where as the bottle with a (straw) hole lets the air go through . The air inside a balloon is under pressure as it is squeezed by the rubber. When you place the inflated balloon on top of the bottle with the straw, the air pressure on top of the bottle becomes higher. That pushes down on the water in the bottle, pushing it through the straw and making the fountain stronger.