Name:

The water runs uphill!

Category:

Physics

• Mechanics

For age range:

6 years and older

For how many?:

4-6 children depending on the materials

Where:

In a room

How long: c. 15 minutes

Preparation/materials:

2 glasses

One small case or box (about the size of your glass)

1 straw to bend

Objectives/ scientific analysis:

The participants gather first-hand experience about fundamental principles of mechanics:

·         Some of these are:

·         Mass and inertia

·         The lever and its significance

·         Frictional forces

·         Inclined plane

·         Uniform and accelerated movement

Steps:

It is best to first try the experiment in a shower tray.

1.      Put the case into the shower tray, with its bottom up.

2.      Fill one glass with water and put it carefully on the box. The second glass is placed on the floor of the shower tray so that it is situated in a lower position than the glass on the box.

3.      Hold the straw into the full glass and suck it. Once the straw is filled with water you shut the end you have sucked with your finger.

4.      Now hold the straw into the still unused glass and remove your finger from the opening.

Scientific explanation:
The water flows through a straw into a second glass. It runs uphill!!!

How does that work?

It seems that the water runs uphill! The explanation is not as difficult as you may think.

The weight of the water in the second, longer part of the straw is a bit heavier than the weight of the part of the straw immersed into water.
The water runs out of the longer part because a force (the so-called cohesive force) ensures that the water stays together. The water particles in the longer part of the straw so to speak drag the water from the shorter part along with them.

That is why the water can even run uphill because at the top where the sharp bend is the water in the longer part pulls down to its side the water from the shorter part.

Possible variations:

Tip: You can also leave out the straw and use a towel instead!

References:

http://www.physicsfuerkids.de/lab1/versuche/bergauf/index.html

Be aware of:
see over

In detail:

Name:

The matchbox and the key ring

Category:

Physics Mechanics

For age range:

5 years and older

For how many?:

2 persons and more

Where:

In a room

How long: c. 20 minutes

Materials:

One light and one heavy object (e.g. a matchbox and a key ring)

A stick, e.g. a long pencil, a pipe, a bicycle pump, a string, about 1 meter long

Aims for the children:

Gather experience with:

·         Mass and inertia

·         Lever and its significance

·         Uniform and accelerated movement

Steps:

You start by attaching both objects firmly to the ends of the string. Then you hold the stick horizontally at eye level in front of you and put the string across. At the same time you hold the light object with your second hand and pull the heavy object up until it almost touches the stick. The light object should be held flat as you see on the picture. Make sure that particularly light objects should never be held above the stick.

What do you think happens if you now simply release the light object? Probably you think the same thing happens that I expected when I heard of this experiment for the very first time. I was sure the heavy object was going to fall down, pulling the other one downwards as well, both hitting the floor. But that is not true!

It is, however, true that the heavy objects falls, but it does not reach the floor. Because the light object winds up the string around the stick, and the whole thing comes to standstill.

Scientific explanation:

First we have to imagine a light object attached to a string hanging down like a pendulum. If the object were simply attached to the stick and you would let it go off it would swing back and forth for quite a while. It would also almost reach the same height from which it was released. The speed at which the object swings depends on the length of the string. You can simply try out that a pendulum with a short string swings faster than a pendulum with a long string.

In our experiment the light object cannot be swinging undisturbed though because the other one pulls the string when falling. Now the string on which the light object is swinging is getting shorter and shorter. And at the same time it is also getting faster and faster. And now (since it is faster) it can rise higher than usually. It flies over the stick to the other side where it builds up new momentum and swings again. Since the string is getting ever shorter the whole process is repeated until the string has been wound around the stick so often that the force with which the heavy object is pulling the string no longer suffices to further pull the other object. This, of course, has to do with friction. And it can easily be tested: after the experiment try to pull up the heavy object by pulling the string without previously unwinding it. This is now much more difficult than before when the string was simply lying over the stick.

Possible variations:

References:

http://www.physicsfuerkids.de/lab1/versuche/streibund/index.html

Be aware of:
Make sure that the objects are not too big so that they do not collide during the winding process. Because if they clash the rolling up stops instantly and both objects fall off.

In detail:

Name:

Water bottle diver

Category:

Physics

Pressure

For age range:

3- 6 years

For how many?:

6 children

Where:

Group room

How long: c.
60 minutes

Preparation/materials:

§         Devise symbols, then draw, paint and cut them out

§         Get the materials

§         Try out the experiment before presenting it to the group

For the large poster, stick together yellow and blue cardboard plastic bottles, plasticine, cardboard, ballpoint covers, water, glasses, paper, pencils, diver, adhesive, scissors

Aims for the children:

Social-emotional:

Children learn to cooperate.

Children give each other mutual support.

Cognitive:

In the introduction phase the children make an input in terms of knowledge.

Children learn, understand how it works.

Good coordination:

The children form plasticine in a way that the diver stands vertically in the water.

The children fill the bottles with water.

Steps:

1.      Introduction:

The painted symbols are in a box. The poster with land and water is located in the middle. One child after the other takes a symbol, says what it is and assigns it correctly. Once all symbols have been stuck to the poster we check whether everything is correct.

2  Execution:

The children take a piece of plasticine and form a ball. A little bit of plasticine is put onto the cover. Every child checks individually whether the diver stands upright. If yes, the children fill their plastic bottles with water. They put the diver inside and close the bottle.

When they press the bottle the diver goes down.

When you release the pressure he rises again.

3. Final phase:

Every child presents its diver once again individually.

Scientific explanation:

How to explain the existence of buoyancy?
In each liquid there is hydrostatic pressure which increases with the height of the standing liquid column. For water the pressure is c. 0,1 bar per meter. For a body (which we imagine in a suspended form in an aquarium) this means that the hydrostatic pressure which is effective from the sides, is counterbalanced. In the graph this effect is illustrated by several pairs of arrows of the same length directed towards the body on the left and on the right.

Above and below the body, however, the pressure is not identical since it goes up with increasing depth. As a result a stronger pressure acts onto the lower body surface than onto the upper one. All in all this results into a force which is directed upwards. If this force is stronger than the weight of the body the body is displaced upward.

Possible variations:

The diver itself cannot be varied except for different colours regarding the plasticine. Introduction and final phase though can be changed just as you like.

References:

Ardley, Neil/Burnie, David: Spannende Experimente aus Natur und Technik, Loewe-Verlag

http://www.kopfball.de/arcexp.phtml?kbsec=arcexp&selExperiment=326&dr=datum#auftr

Be aware of:
Do not shake the diver since otherwise he drowns. Do not use any Aldi plastic bottles.

In detail:

Name:

The climbing tube

Category:

Physics Mechanics

For age range:

5 years and older

For how many?:

4-6 children at the same time

Where:

In a room

How long: c.
45 minutes

Preparation/materials:

A cardboard tube, the best thing you can use is a cardboard tube for posters with plastic covers on both ends, but you can also use a cardboard tube from kitchen rolls and two discs made of cardboard.

A wooden stick which must be as long as the diameter of the tube

Two drawing pins

A string

Aims for the children:

§         Lever principles

Scientific explanation:

Installation

Usually a lifting block consists of two sets of connected blocks. The hauling rope is thread in, in such a way that it goes alternately around one block of each set. The arrangement or the different size of the blocks ensure that different parts of the rope line do not rub against each other. One set (mostly swivelling) is attached to a supporting structural element of the building whereas the other set, on which there is a hook for the load, hangs at the rope.

Even for horizontal purposes lifting blocks can be used in connection with a rope winch.

Effect

The force-reducing effect of the lifting block is based on lever principles. Due to the arrangement of several parallel rope pieces the hoisting height of the load is smaller than the length of the pulled rope. The force necessary to pull is inversely proportional to the by 1 increased number of movable blocks. i.e. if the lifting block has one movable block the force required to pull is halved: 1 ÷ (1 + 1) = 1/2. When using three movable block only one fourth of the expenditure of force is necessary but you have to pull four times longer.
Theoretically the required expenditure of force could be reduced in such a way that an ant could lift an elephant when using a lifting block. However, there are a number of obstacles to that:

1.                              The space required for such a lifting block would be beyond norm.

2.                              The distance would be so long that it cannot be covered in an ant’s lifetime.

3.                              The own weight of the blocks and the rope have to be lifted as well, i.e. additional potential energy has to be summoned up.

Since the blocks are never fully frictionless a part of the work is turned into frictional heat. With a certain number of blocks this frictional heat absorbs the entire energy which is used. This would stop the ant from advancing.

Steps:

First, you put the wooden stick crosswise inside the tube and fix it with the drawing pins. Then, through a small hole in the upper cover you pull a piece of string into the tube and tie it there into a loop. Through the lower cardboard disc you also pull a piece of string into the tube. Here the string goes upward through the loop of the other string, then back downward, around the wooden stick and back upward; finally it is attached to the other string with a knot.
If you have used the cardboard discs instead of plastic covers you now have to glue them together with the tube.

Finally you paint the tube – and your climbing tube is ready. If you now pull the lower string the tube moves upward.

Possible variations:

Build lifting blocks in an outdoor area and transport weights.

References:

http://www.physicsfuerkids.de/lab1/versuche/kletterrohr/index.html

http://www.net-lexikon.de/Flaschenzug.html

Be aware of:

In detail:

This inner construction is called “lifting block”.

Name:

Marble tower machine  Marble Tower 1

Category:

Physics:

Mechanics

For age range:

4 years and older with instructors

For how many?:

5 children and more

Where:

In a room

How long:
Project duration c. four weeks

Materials / preparation:

Wood plate, wood lath in different size and thickness, 4 boards, plastic hoses, cardboard boxes from Ikea, small materials (e.g. crown caps, broken glass, cotton wool). Wire netting, newspapers, Velcro strip, bicycle tyres and tubes, enormous quantities of hot-melt adhesive, nails, screws, wire and other small materials.

Aims for the children:

Implementation of fundamental principles in mechanics which have been shown in the previous experiments

Steps:

First a drawing was made at the blackboard, and ideas collected. Based on this drawing we provided the material.

Then the three-storey skeleton structure was set up. Into this basic structure you install one after the other the three departments from top to bottom – following the run of the marble.

Individual elements were designed in colour.

In a parallel step the domino-department and the lift were developed.

On the roof of the tower we have installed strips of wood with a groove in the middle through which the marble runs.

Different holes had to be drilled into the inserted ceiling in order to enable the transition of the marble between the individual departments.

In department 1 the tunnels had to be attached in a suspended way which was done with kite string.

The hose in the second department was relatively easy to fix, but a regular slope (gradient) is important so that the ball does not get stuck.

Department 3 was easy to integrate. However, the option to have the ball pass on the right or on the left side was indeed a bit more difficult to achieve so that in the end we have solved the problem with the string.

No difficulties occurred when building and installing the set of dominos. But directing the ball in a way that it hits the first domino stone and thus triggers the chain reaction was extremely tricky and still requires a lot of skill when setting up the machine!

The construction of the individual elements forming the lift was not problematic. But the installation of the whole system sometimes is very dramatic and not without any risk!

Scientific explanation:

No changes versus the last experiments in relation to this topic

Be aware of:
see over

Possible variations:

References: BBS VII – Sozialwesen -, Böcklinstraße 29 38106 Braunschweig

In detail:

1.      Pull the string (1) hanging down at the side. This triggers a small barrier (2) which at the top level blocks the track of the marble. Now released the marble starts rolling down the track. After a first short trajectory it reaches its destination and hits the first of a set of dominos (3). The marble falls into a cup (4) where it is caught.

2.      A chain reaction is triggered and all dominos fall. In order to bring them back into their position you pull the small strings (5) and the dominos are put upright again.

3.      In the basket (6) of the lift (7) there is a second marble. The lift is pulled up to the second track. At its end the marble reaches a cup (8) and falls into department 1.

4.      Department 1 consists of a system of long, rectangular cardboard tubes (9).

5.      Points are integrated into this system by which the marble can be sent onto two different trajectories.

6.      In department 2 the marble runs through a long, transparent hose (10) made of hard plastic.

7.      At the beginning of department 3 the marble gets once again to a long, rectangular cardboard tunnel (11). At the bottom side of the tunnel you can decide by pulling a string whether the ball should run to the left or to the right.

8.      On the right side there is a “flipper” (12), on the left the “zigzag-track” (13).

9.      A tube (14) is located at the end through which the marble gets back into the lift basket.

Name:

Marble tower 2 - going up hill and down dale

Category:

Physics

Mechanics

For age range:

4 years and older with instructors

For how many?:

5 children and more

Where:

In a room

How long:
Project duration c. four weeks

Wood plate, wood lath in different size and thickness, 4 boards, plastic hoses, cardboard boxes from Ikea, small materials (e.g. crown caps, broken glass, cotton wool). Wire netting, newspapers, Velcro strip, bicycle tyres and tubes, enormous quantities of hot-melt adhesive, nails, screws, wire and other small materials.

Aims for the children:

Implementation of the fundamental principles in mechanics which have been shown in the previous experiments.

Steps:

First we have built the skeletal structure for the marble tower machine. This skeletal structure consists of a wood plate supported by two boards on one side. On the other side we have screwed in a wooden peg to give the plate more stability. All elements were attached with screws.

After passing the points the marble runs through one of 4 hoses onto one of 4 different tracks. All tracks consist of one wood plate each, all of the same size. The 4 tracks have different topics, e.g. road with cars, stream with a bridge or ski jump. The topics can be varied as you like. For the construction of the tracks we have used residual materials from wool, cotton wad, and decoration stuff for model railways.

Scientific explanation:

See previous experiments and projects

Possible variations:

After the different tracks the marble falls onto a wood board which was nailed in a sloping position against the main plate. The marble now runs to the side. Here it falls onto a long wood board. The marble is stopped by a barrier.

With a rubber band the marble is shot onto a ramp made of bicycle tyre. From here the marble is transported upwards by a film box attached to a clothesline. The clothesline with the film box is fixed to two bicycle tyres placed on top of each other. The upper bicycle tyre can be turned by using a small crank. Due to the rotation of the upper tyre the lower tyre also moves, and the film box is conveyed upward.

Once the marble has reached the upper position again it falls out of the film box and into a funnel. The marble crosses the funnel and runs through the hose back to the first track with the cardboard boxes. The cycle starts anew.

Be aware of:

References:

BBS VII – Sozialwesen -, Böcklinstraße 29,  38106 Braunschweig

In detail: