Measure out 1 cup of cornflour and place it in a bowl.
Measure out ½ cup of water.
Slowly add some of the water to the cornflour and mix with your hands.
Then add some more water and keep mixing with your hands.
Continue adding water and mixing until your slime has the right consistency.
If gets is too runny you can add some more cornflour.
Add about 10 drops of food colouring until your slime and mix it.
You can store your slime in a plastic container with a lid. Your slime might still dry out a bit over time. If this happens you can just add some more water.
Mixing cornflour and water gives you a slime that behaves very peculiar. If you touch it very lightly it feels liquid like water. If you hit it very hard and fast it feels solid like a rubber ball. The slime reacts differently depending on the force that acts on it. The bigger the force, the harder the slime. The smaller the force, the more liquid the slime behaves. These kind of liquids are called “non-Newtonian”.
Shine the torch through the beaker of water. It looks white like the sun when it is high up in the sky.
Pour a little milk into the water in the beaker.
Stir the water gently, so that it all goes slightly white.
Shine the torch through the water again. It will look different.
Again, add a bit more milk to your glass and stir again.
Shine the torch through the water again and observe what the light looks like now.
You can repeat the steps of adding milk, stirring and shining a light through several times.
When the sun is low in the sky, in the morning and the evening, its light passes through more air than at other times of day. Tiny particles of air stop much of the sun’s light. Only orange and red light gets through. The same happens when you shine your light through the milk-water mixture. Tiny particles from the milk stop most of the light. Only some colours pass through. Which colours did you see?
Place the open bottle in the freezer for 10 minutes.
Remove the bottle from the freezer and moisten the rim of the mouth with some water.
Cover the rim of the coin with some water, so that nor air can pass through.
Place your hands around the bottle.
Observe what happens.
You will be able to observe the coin moving as if a ghost was in the bottle. The cold air in the bottle is warmed by your hands and expands. The coin and water prevent the air from escaping the bottle. However, if the pressure gets high enough, the coin acts like a valve and moves releasing the warm air from the bottle.
You can watch the video for this experiment on YouTube:
Place the outside box of the match box upright on a table.
Put the inner box upright on top of the outside box.
Try to smash the construction from the top using your fist. What happens?
Now, place only the inner box of the match box upright on a table.
Try to smash the inner box with your fist. What happens now?
When hitting only the inner box, it will smash. However, if inner and outer box are placed on top of each other, they do not smash, but fly off undamaged in a high curve.
The reason is that the inner box can divert pressure to the outer box when both are placed on top of each other. The boxes fly off because their edges are not rigid, but flexible. The elastic energy from the edges is transferred to kinetic energy.
If one box is placed by itself, pressure cannot be diverted and the box is smashed.
When objects are not moving or moving at a constant speed, the forces on them are balanced. We are going to try and balance the force of gravity and the force from a hair dryer’s air stream on a table tennis ball.
You will need
1 Table tennis ball
1 Hair dryer
What to do
Point the hair dryer upwards and turn it on.
Carefully place the table tennis ball in the air stream.
The table tennis ball should float in the hair dryer’s air stream.
You might have to play with the strength of the air flow to get things exactly right.
If you get it to work, try to tilt the hair dryer and see how far you can tilt it, before the ball falls off.
When the table tennis ball is floating the forces of the hair drier’s air stream and gravity are exactly balanced.
Arrange the baking soda in the bowl around the tea light using the tea spoon.
Light the tea light.
Slowly add vinegar to the baking soda around the tea light. Be careful not to put the vinegar directly into the flame.
Observe what happens to the candle.
When vinegar reacts with baking soda, the gas carbon dioxide is formed. Carbon dioxide is heavier than air and stays in the bowl. Carbon dioxide gas replaces the air with the oxygen needed for the tea light’s flame in the bowl. Finally, the non-flammable carbon dioxide gas smothers the flame.
Our eyes can only see a certain amount of pictures per second. They are actually quite slow. This is why we cannot see objects that are moving extremely fast. In this experiment we are going to use the slowness of our eyes.
You will need
Pens or colouring pencils to draw a picture
What to do
From the paper cut two pieces with the same shape and size.
Draw two different pictures on the two pieces of paper that can also go together, for example a rabbit on one piece of paper and grass on the other. You could also do a bowl of water on one piece and fish on the other one. Or a bird on one piece and a tree on the other one for the bird to sit on.
Tape both pieces of paper on either side at the end of a pencil. The pictures need to face outside.
Now rub the pencils between your hands as if it was a stick that you want to light a fire with.
Look at the pictures.
You will see both pictures combined together, for example the rabbit sitting on the grass or the fish in the bowl.
The reason this works is that our eyes are too slow to follow the fast movement of the pictures and can only see a limited amount of pictures per second.