Winter

Polish group during winter holiday.

It has been quite cold for few days, about -20 degrees C.

Whirl of water

Materials needed: two plastic bottles 1,5 l and strong adhesive tape.

At the beginning you need to make the hole in the cups then fill a bottle with water and spin. Later you join the two bottles and twist tape around. At the end invert the bottles, shake them and observe the water whirl.

cohesive forces

Necesary materials:
big bowl, water and tablet's packaging.

To make this experiments pour some water into the bowl. From the tablet's packaging cut out the places where tablets were and put them carefully onto the water. Observe their movement. At first we will see interaction of just two elements and later the others.

The elements cut of the tablet's packaging represents molecules, which attract each other. Among the particles we can observe forces of the molecules interaction. They can attract each other and therefore they are also called cohesive forces. In fact the interaction among the molecules is the effect of the surface tension of liquid.
You see that one of pieces haven't attracted each other. It is because it is partially submerged.

Ping Pong

To our experiments we need: ping - pong ball and hot water.

First we make a dent in ping - pong ball. After that we put it into the hot water.
The ping - pong ball is round. Why? Because air in the ping-pong ball expands.

Balloons

Needed materials:
2 balloons, piece of the thread
We blow up balloons and hang them up on threads close to each other but without direct contact.
Next we rub them energetically with piece of fabric or dry paper.
Description:
On the basis of this experiment it is possible to state that rubbing some substances is triggering changes causing interaction. It is possible to divide electrifying materials in two categories.
Materials belonging to the same category after charging are pushing off, and materials belonging to all sorts categories attract each other.

Cyprus, our beautiful island