— Arvind Gupta,
author of Matchstick Models and Other Science Experiments
Here are some exciting experiments and toys for your creative minds. To be a part of them, you only need things like matchsticks, buttons, etc., which you might already be having in your precious possession. Follow the exercises and see, for instance, how a match box becomes a ‘magic box’. And what’s more, you can discover some of the most important scientific principles this way!
So just go ahead and let the scientist in you take over…
Any mecanno, even of the most expensive sort, when stripped of its frills and fancies essentially reduces to a few building blocks and couplings. These basic blocks and couplings can be joined together in a variety of ways to create an array of different structures and configurations.
Matchstick Models uses matchsticks as the basic structural members and bits of cycle valve tube as the joints. Cycle valve tube is sold by weight in cycle shops. A 100 gms. packet cost between Rs. 5 to 6, and contains about 16 metres of cycle valve tube.
Choose either from indexed menu below or just click NEXT Button for the ride.
[ Joint – of – two ] The flexible joint – of – two can be used for illustrating angles – acute, right, obtuse and straight angles.
[ Rigidity of a triangle ] Why is the triangle the only rigid shape, where as the hexagon, the pentagon, the square and the rectangle are all wobbly and shaky?
[ Triangles in use ] Triangles do not shake, that is why they are used in Railway bridges, electric towers and even village huts, which are all arranged in the triangular form.
[ Joint – of – three ] The tetrahedron is one of the most fundamental structures found in nature.
[ Rigidity of a tetrahedron ] Check out – where is it used in our daily life?
[ Length ] How would you measure the length of an object without a scale? Do it yourself.
[ Volume ] It’s very easy to measure volume. Learn to make standards for measurements.
[ Weight ] Make a weighing balance using leaf cups or empty polish tins for the pan.
[ Matchbox trolly ] You can do a whole range of experiments in dynamics, like the roll – and – drag friction experiment, etc. with this.
[ Matchbox tipper truck ] Lets make a working model of a tipper truck. The cut shell becomes the driver’s cabin. Make a hole in the driver’s cabin and…….
[ Tipper and trailer ] Similarly you can convert the matchboxes into wagons on wheels.
[ Inertia pump ] The cheapest water pump of the world. Design it at home…
Cut about 1.5 cms. long pieces of the valve tube. Scrape the sulphur from the matchstick heads with a blade.
Push one end of a matchstick through a valve tube piece. You’ll find that the matchstick slides in snugly in the valve tube. Push a second matchstick through the other end of the valve tube piece. The ends of both the matchsticks should touch head-to-head, inside the valve tube.
This is a joint of two matchsticks, or simply a joint-of-two. The flexible joint-of-two can be used for illustrating angles acute, right, obtuse and straight angles.
Three matchsticks and three valve tube pieces in a row can be looped together to make a triangle.
As the matchsticks are the same length the triangle turns out to be equilateral – with all sides equal. All the angles in this triangle are equal and measure 60 degrees.
Other shapes like isoceles triangles, squares, rectangles, pentagons, hexagons and octagons can be made by joining together more matchsticks and more valve tube pieces. A whole range of polygons can be made in this way.
Rigidity of a Triangle
Try pressing a pentagon between your thumb and the middle finger. What happens? – The pentagon distorts into a boat shape. If you hold it with both the hands and flex it, then it shakes. It is a dancing shape.
Now press the opposite corners of a square. What happens? The square is unable to resist the pressure. Its right angles give way and distort into a rhombus, or a diamond shape.
Finally, try pressing or shaking the triangle. What happens? The triangle does not budge at all. Its shape remains intact. In short, a triangle remains a triangle.
The triangle is the only rigid shape. All other shapes like hexagons, pentagons, squares and rectangles are wobbly and shaky.
How can the square be made rigid?
Insert a long babool thorn (or a long needle) through two diagonally opposite valve tube joints of the square. The thorn divides the square into two triangles. The triangles make the square rigid. How can the ‘dancing’ pentagon be made rigid?
Triangles in Use
The triangle does not shake. The triangle does not distort. The triangle is the most rigid shape. This rigidity of triangles make them very useful in making houses, bridges and a number of other structures which we use in daily life.
Most roof trusses of village houses are made of bamboo and wooden beams. The bamboos and beams are always arranged in triangles. The trusses are never arranged in squares, pentagons or hexagons. What would happen if the roof truss was divided into squares? The square truss will not be able to support the weight of the roof. Because of the weight of the tiles, the squares will buckle into diamond shapes and the truss will collapse.
Similarly, the structural members of railway bridges and electric towers are divided into triangles. The triangles make them rigid.
Pierce a hole in the valve tube joint-of-two by poking it at right angles with a babool thorn. Insert a third matchstick (slightly sharpened at the end) in this hole. This is a JOINT-OF-THREE, or simply a ‘T’ joint.
Take the equilateral triangle and poke holes in its valve tube joints with a babool thorn. Now insert the three matchstick ends of the ‘T’ joint in the holes of the triangle.
The ‘T’ joint and the equilateral triangle thus put together form a new structure. It has 4 corners, 6 edges and 4 distinct surfaces. All its surfaces are equilateral triangles.
As triangles are rigid so, a structure built entirely of triangles must be very rigid too. And indeed, it turns out to be true. This structure is called a TETRAHEDRON and is one of the most fundamental structures found in nature.
In a similar manner join together two separate triangles using three matchsticks to make a PRISM.
Join two separate squares with 4 matchsticks, to make a CUBE.
Make many more structures using the joint-of-three.
Rigidity of a Tetrahedron
The tetrahedron is the strongest structure found in nature. It has several uses in daily life. Actually, people have been using the tetrahedron for centuries in different kind of structures.
For instance, you must have seen grain bags being weighed in the market. Often the weighing balance is suspended on a tripod of three bamboos. This tripod has a structure of a tetrahedron.
Hawkers often display their wares on trays which are kept on bamboo tripods. You must have also seen three legged camera tripods and stools. These are just a few examples of the use of tetrahedrons.
The length of a matchbox is a good estimate of 2 inches, or 5 centimetres. It can be used for estimating length. Half a matchbox would measure 1 inch, or 2.5 cms. The length of six matchboxes kept end-to-end would almost be 1 ft., or 30 cms.
Like the matchbox there are several other common objects which can be used as good estimates for measurement of length.
Every matchstick has a square cross-section. Each side of the square measures 2 mm.
The postcard is always 14 cms. long and 9 cms. broad.
Normal bricks are 9 inches long.
The length of a cycle spoke is approximately 1 ft., or 30 cms.
Coins have standard dimensions. They can be used as pretty good estimates for measurement of length. For instance, a circle drawn around a 50 paise coin is almost 1 inch, or 2.5 cms. in diameter.
You must verify the lengths of the above items for yourself by actually measuring them with a scale. Later on, even if you do not have a ruler at hand, you can always use some matchboxes, coins, postcards etc. for making estimates of length. Measure the length of your hand-span.
Dip a little cotton ball in oil and rub it on the matchbox drawer. Soon the wood and the paper of the matchbox drawer will absorb the oil. Keep the drawer in the sun for drying. Oiling makes the drawer waterproof.
This drawer when filled with water holds approximately 20 millimetres of water. The matchbox drawer is a good estimate for measuring 20 ml. You can use this as a rough standard for measuring volume.
Stick a strip of white paper along the length of a broad-mouthed bottle. Now fill a matchbox drawer with water and pour it in the bottle. Indicate the water level in the bottle by marking a line on the strip of paper. This mark will indicate 20 ml.
Add further drawers full of water in the bottle, and each time keep marking the levels of 40 ml., 60 ml., 80 ml., 100 ml. etc. You can draw a line midway between the 40 ml. and 60 ml. marks. This midway line will indicate the 50 ml. mark.
This bottle now becomes a graduated cylinder for measurement of volume. Fill the bottle upto the 100 ml. mark, and then pour it out in a bucket. Repeat this ten times. Now the water in the bucket will be 1000 ml. or 1 litre.
Make a weighing balance using leaf cups or empty polish tins for the pans. Ensure that the balance point is equidistant from the two pans. Only then will the balance weight truly. Now keep one oiled matchbox drawer on each of the pans. As the drawers have the same weight the beam will remain horizontally. Fill the left-hand drawer completely with water. The drawer will hold 20 ml. of water. And as one millilitre of water weighs one gram (density of water) so, 20 ml. of water will weigh 20 gms. It amounts to putting a 20 gms. weight in the left-hand pan. Place some junk wire in the right hand pan so as to balance the beam. The wire shall now weigh 20 gms.
Straighten out the wire and cut it into half and quarter lengths to make 10 gms. and 5 gms. weights.
You can similarly make 50 gms. and other weights.
Several daily use objects have standard weights.
A brand new sealed matchbox is a good estimate for 10 gms.
50 unburnt matchsticks approximately weigh 5 gms.
10 unburnt matchsticks approximately weigh 1 gm.
1 unburnt matchstick is a very good estimate of 0.1 gm.
The approximate weights of some of the coins are:
One Rupee coin (old) 8.0 gms.
One Rupee coin (new) 6.0 gms.
50 Paise coin (old) 5.0 gms.
25 Paise coin (old) 2.5 gms.
Heat the tip of a paper pin and pierce it through the centre of a cheap quality plastic coat/pant button ( it is necessary to use cheap quality buttons, because the plastic melts easily ). Now heat the head of the pin. Apply pressure on the rim of the button with your thumbs and press the hot pinhead against the ground. The pinhead goes and firmly embeds itself in the centre of the plastic button. If however, the pin comes out at an angle, it can be made ‘square’ (at right angles to the button) while it is still hot and pliable.
The pinhead firmly anchored in the centre of the button makes a good ‘drawing pin’. Now, cut and insert a small piece of used ball pen refill in the drawing pin’. The refill will serve the purpose of a bearing or a ‘bush’.
Heat the ‘drawing pin’ tip in a candle flame once again and embed it in the centre of another cheap quality plastic button. This assembly consists of two button wheels, one paper pin axle and a ball pen refill bearing. Make two such wheel assemblies. Place a new matchbox on their refill bearings. Put a rubber band around to anchor the wheels to the matchbox.
With the help of the matchbox trolley you can do a whole range of experiments in dynamics, like the roll-and-drag friction experiment, inclined plane experiment etc.
Matchbox Tipper Truck
You must have seen tipper trucks unloading sand, stones or coal. You can readily make a working model of a tipper truck. Take a matchbox and separate its drawer from the outer shell. Cut the outer shell so that it fits into the drawer. The cut shell becomes the driver’s cabin. Slip another matchbox outershell on this drawer. This will make the body of the tipper.
Take another drawer. Cut and bend its tongue into the body of the truck. You can either stick this tongue inside this body, or else you can wedge it with a piece of matchstick. The drawer can now swivel on the body and make the loading platform of the dumper truck.
Make two pairs of wheels using buttons, needless and refills. Cut a rubber eraser into four pieces. Stick these pieces in two pairs below the body. The distance between each pair should be equal to the thickness of a ball pen refill. Fix the wheel pairs between the rubber pieces. Insert a matchstick from the hole in the driver’s cabin. Load some pebble cargo in the tipper truck.
On pressing the matchstick lever from inside the driver’s cabin, the loading platform will be raised to unload the cargo. On pushing it the tipper truck will run very smoothly.
Tipper and Trailer
The matchbox tipper is an illustrious example of children’s creativity. It was designed by the children of contract worker’s in the iron-ore mining township of Dalli-Rajhara. Most of these children do not go to school, but every day they see hundreds of dumper and tipper trucks carting ore from the mines to the railway station. An urge to imitate the adults must have prompted the children into designing this model marvel of the tipper truck using just two matchboxes.
Matchbox drawers can be similarly converted into wagons on wheels. Several such wagons could be coupled together to trail behind the tipper truck.
This simple pump was designed by Suresh Vaidyarajan. Any hollow tube – PVC, metal, bamboo, or even a one foot long Papaya stem can be made to pump up water. Hold the tube with your left hand and move it up and down into a bucket of water. Keep the palm of your right hand on the top of the tube and open and close it with each up and down reciprocation. Soon water will start squirting out. In this case the up-down motion of the left hand does the pumping while the right palm acts like a valve. The use of the hand palm gives a very good physical feel for a valve.
Try and find the maximum height to which you can lift water by this means. Such pumps are still used in some parts of Andhra Pradesh.
Category: Craft Activities for KidsTags: arvind gupta • pvc < Previous Post | Next Post >