Home Experiment: Halloween Slime

You will need

  • Bowl
  • Measuring cup
  • Spoon
  • 1 cup of cornflour
  • ½ cup of water
  • Food colouring (you can choose which colour)
  • Plastic container with lid for storage

What to do

  1. Measure out 1 cup of cornflour and place it in a bowl.
  2. Measure out ½ cup of water.
  3. Slowly add some of the water to the cornflour and mix with your hands.
  4. Then add some more water and keep mixing with your hands.
  5. Continue adding water and mixing until your slime has the right consistency.
  6. If gets is too runny you can add some more cornflour.
  7. Add about 10 drops of food colouring until your slime and mix it.
  8. 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.

Background

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”.

You can watch the experiment as a video here:

Home Experiment: Make a Sunset

You will need

  • 1 Glass
  • Milk
  • Water
  • Torch
  • Spoon

What to do

  1. Shine the torch through the beaker of water. It looks white like the sun when it is high up in the sky.
  2. Pour a little milk into the water in the beaker.
  3. Stir the water gently, so that it all goes slightly white.
  4. Shine the torch through the water again. It will look different.
  5. Again, add a bit more milk to your glass and stir again.
  6. Shine the torch through the water again and observe what the light looks like now.
  7. You can repeat the steps of adding milk, stirring and shining a light through several times.

Background

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?

You can watch this experiment as a video here:

Air Pressure Experiments

You will need:

1st experiment:

  • Glass bottle
  • Balloon

2nd experiment:

  • One piece of card board
  • Glass
  • Water

What to do:

1st experiment:

  1. Stretch the opening of the balloon over the rim of the bottle’s mouth. Make sure that the body of the balloon is inside the bottle.
  2. Try to blow up the balloon.
  3. The air in the bottle has nowhere to go and pushes on the balloon. This increases the pressure in the bottle when you try to blow up the balloon and you will not be able to blow it up.

2nd experiment:

  1. Pour water into the glass until it reaches the rim of the glass.
  2. Place the piece of card board on the glass. Hold it down so the card board covers the rim all the way around.
  3. Still holding the card board, move above a sink.
  4. Turn the glass upside down while still holding the card board. Then let go of the card board.
  5. Air pressure forces the card upwards, against the glass. The pressure is strong enough to stop the weight of the water pushing the card away.

You can watch a video for this experiment here:

Home Experiment: Ghost in the Bottle

You will need

  • One glass bottle
  • One coin (2 Pounds or 2 Euros work well)
  • Freezer

What to do

  1. Place the open bottle in the freezer for 10 minutes.
  2. Remove the bottle from the freezer and moisten the rim of the mouth with some water.
  3. Cover the rim of the coin with some water, so that nor air can pass through.
  4. Place your hands around the bottle.
  5. Observe what happens.

Background

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:

Home Experiment: The Unbreakable Box

You will need

  • One empty match box

What to do

  1. Place the outside box of the match box upright on a table.
  2. Put the inner box upright on top of the outside box.
  3. Try to smash the construction from the top using your fist. What happens?
  4. Now, place only the inner box of the match box upright on a table.
  5. Try to smash the inner box with your fist. What happens now?

Background

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.

You can watch a video for this experiment here:

Home Experiment: Balancing Forces

Background

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

  1. Point the hair dryer upwards and turn it on.
  2. Carefully place the table tennis ball in the air stream.
  3. The table tennis ball should float in the hair dryer’s air stream.
  4. You might have to play with the strength of the air flow to get things exactly right.
  5. 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.
  6. When the table tennis ball is floating the forces of the hair drier’s air stream and gravity are exactly balanced.

You can also watch this experiment on YouTube:

Home Experiment: Fire Extinguisher

You will need

  • Tea light
  • Tea spoon
  • Small bowl
  • Vinegar
  • Baking soda
  • Match to light the candle

What to do

  1. Place the tea light in the middle of the bowl.
  2. Arrange the baking soda in the bowl around the tea light using the tea spoon.
  3.  Light the tea light.
  4. Slowly add vinegar to the baking soda around the tea light. Be careful not to put the vinegar directly into the flame.
  5. Observe what happens to the candle.

Background

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.

You can watch this experiment as a video here:

Vinegar and Baking Soda Bomb

Background

Vinegar is an acid and reacts with baking soda to form salt, water and carbon dioxide gas. The extremely fast formation of carbon dioxide gas will cause your zipper back bomb to explode.

You will need

  • Plastic zipper bag
  • Vinegar (any kind will do, but you will need quite a lot of it)
  • Baking soda
  • Cup, glass or mug
  • Table spoon

What to do

  1. Go outside to do this experiment.
  2. Check your zipper bag to make sure that it does NOT have any holes or rips before the experiment.
  3. Fill your glass or mug completely with vinegar
  4. Pour the vinegar from your glass or mug into the plastic zipper bag.
  5. Place the zipper bag on the ground.
  6. Add one heaped table spoon of baking soda and quickly close the bag.
  7. Quickly step away from the zipper bag and watch what happens.

You can watch this experiment here:

Match Boats

You will need

  • 1 Bowl
  • Washing-up liquid
  • 1 Match
  • Water
  • 1 Knife

What to do

  1. Fill the bowl with water.
  2. Split the match slightly at its lower end using the knife.
  3. Smear the split end with some washing-up liquid.
  4. Place the match in the water and watch what happens.
  5. The soap will dissolve slowly in the water which causes a backwards movement of the water molecules. This lets the boat move forward.
  6. If you want to repeat the experiment, change the water in the bowl and use a new match.

You can also watch this experiment here:

Optical Illusion – Home Experiment

Background

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

  • Paper
  • Pencil
  • Pens or colouring pencils to draw a picture
  • Tape
  • Scissors

What to do

  1. From the paper cut two pieces with the same shape and size.
  2. 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.
  3. Tape both pieces of paper on either side at the end of a pencil. The pictures need to face outside.
  4. Now rub the pencils between your hands as if it was a stick that you want to light a fire with.
  5. Look at the pictures.
  6. 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.

You can also watch this experiment as a video: