For PBIS students

Dear students PBIS

I have set up this page to be in contact with you even in the times, when you are not allowed to go to school. In our school I not only prepare experimets for Physics but in Makers’ Space I help students to realise their extended essays, group four projects and other practical activities. Some students work on my projects or they come here to realise theirs. You can see pictures here – on the Dream Job page.
Your activities are very limited these days and theoretical subjects coming out of your computers may be tiring a little bit.

For the begining I have prepared three tasks that you can make yourselves at home by using ordinary materials and tools you can find in the most households.
I would like you to 

– Try your dexterity, some may be a challenge to you

– Learn some theory about how it works

– Enjoy a lot of fun

BOOMERANG

Boomerangs were invented by the Aboriginese and were used for hunting birds flying in flocks, as musical instruments and also as toys. And this is just the reason for your effort to make it.

But let’s have a look at the history of boomerang:

https://www.nma.gov.au/defining-moments/resources/earliest-evidence-of-the-boomerang-in-australia

BOOMERANGS were used in the Stone Age also in Europe (probably non-returnable). But in Australia the Stone Age only finished when the Europeans arrived there and at many places much later:
Let’s have a look at the fascinating video of Aborigines filmed black and white in the 1950th:

But how did the Aborigines make the boomerangs and spears?
Let’s have a look at the short 6min video:

The boomerangs used for playing could look like these ones:

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And now, look at our paper boomerang that you can make yourselves within an hour and fly it even in your room:

What things do you need to make it?

A piece of hard paper – the best one is from the paper box in which shoes are sold. Compasses, ruler.

Draw 3 axes by 120* a decide the dimensions:  The mine are: R= 7.5cm, r= 1.5cm, draw the outline and cou it out.  (Bigger boomerangs also work)

The wings must be bent! You will make it by a spoon, but the wing must be put on two layers of the scrapped paper.

Make the rest of the shape by hands.

   I am left handed

Important: How to throw you boomerang!
The boomerang must be spinning as fast as possible but must NOT be thrown at long distance, otherwise it will turn upside down
.

   Thrown by your right hand

How a boomerang works so that it can return – sometimes back to your hand?

v – Peripheral speed,  s – Speed of the centre of gravity, omega – angular speed.

On the left side the peripheral speed and the speed of the centre of gravity will be  added. On the right side they will be subtracted. So, the speed on the left side is higher.
The bent profile of the wing will cause the uplifting force as the distances between molecules of air are bigger above the profile, than under the profile. So the pressure above the profile is lower then under the profile. The difference of the pressure makes the boomerang go up. But the higher force on the left makes the boomerang incline. And on its way down it is returning  back to you.                                     Your boomerang will be returning even in you  room.
Try, try, try. As much spinning as possible. You will learn from your mistakes and youy will succeed.

Good luck with your selfteaching and enjoy the throwing.

Throwing the boomerang:

 

Jiri

Any questions?  – Email me on jiritom@seznam.cz

 

KITE

In Autum boys and girls often fly a kite. Why not to make your own one?

There are many instructions how to make a kite on internet. I would like to present you a small one, that you can make just on your kitchen plastic meat board from ordinary skewers 30cm long (available in all supermarkets) and a plastic foil. In addition you will need white craft glue and chemopren glue and, of course, a long thread.

  The finished kite without a tail

                       

1. Cut  5 skewers into thirds = 15 pieces of the same length.
2. Put long skewers on the meat board 9,5 cm appart, put a weight on them and put the short pieces
accross to make a regular “ ledder”.                                                                                                                 3. 3. Glue the joints of the ledder by the white craft glue and let it get dry for at least one hour.

                  

4. Make two ledders.

5. Put the ledders one side down 9,5cm appart, put some weight on them, make sure they are standing
in the right angle and are parralel a put short pieces accros and add some drops of glue on the joints.
You will probably have to do it in two steps. One ledder bar will be omitted. This work will demand
your patience but as a student of PBIS you have it enough.

  Add the long skewer, glue it and the kite skeleton is ready. When it is finished, you can take it to your hand and put more glue around each joint.

6. The crisscross thread will make the skeleton stiffer.
Use a good, strong thread, the same will be used for flying the kite.
Cut the marked lines, glue the skewers and wind the foil around it, step by step on the left and then on the right cube.


Two cubes are finished.
Now, lay the foil on the table so that it is smooth, not wavy.

Put the glue on the skewers that are in contact with the foil.
Outline the shape of the kite with some addition of 1cm and cut it out.
Put the glue on the string and the edges of the foil and bend the foil over the thread.
Cut the middle square of the foil but about 1cm smaller on each side.
Put some glue on the skewers and bend the foil around.
Your KITE is finished – nearly.

The last step is – to make a tail, to attach a thread and to fly your new kite.