Rising water

This experiment requires the assistance of an adult.

For this experiment, you’ll need a bowl, tape, some water, a glass (that’s taller than the candle) and a candle (that must be handled only by an adult).

We begin by applying some tape to the bottom of the candle and sticking it onto the centre of the bowl. Now fill the bowl with water until the water is about an inch or two in height.

Ask an adult to light the candle. Place the glass over the candle and watch what happens inside the glass.

Can you see the water rise in the glass?

This occurs because of a few events. The candle’s flame uses up the oxygen in the air inside the glass as it burns, however, the flame also heats up the air and the air expands. The space consumed by the expanded molecules of air is almost equal to the space made available from the consumed oxygen and no change takes place in the level of the water in the glass. When the candle goes out, the air cools down and the air contracts, this makes a vacuum and the water quickly rushes in to fill up the space available.

There’s a quick demonstration of this experiment performed by Sick Science!, here it is:

An object’s ability to float

What you’ll need for this experiment is a transparent glass or tumbler that’s filled with water, an egg and salt.

First, check if the egg floats in the glass without doing anything to the water, it will not.

Now add some salt to the water and stir it until it dissolves, check if the egg floats now.

If it doesn’t, add some more salt and try again.

Keep adding more salt until the egg floats.

The egg eventually floats because at that point the density of the salt water is greater than the density of the egg.

This phenomenon occurs naturally in the dead sea, where the salt content in the water is so high that even humans float on it because we aren’t as dense as the salt water.

Is it clear now that the density of an object is the factor that accounts for buoyancy, if an object is denser than the liquid, it sinks. If the liquid is denser than the object, it floats.

Tip: If you add more water to the glass the density of the solution will reduce and you can see the egg sink a little lower.

You can also add different amounts of salt in multiple glasses so you have a line of eggs suspended at different levels.

Here’s a neat video from ‘Sick Science!’ that demonstrates this experiment:

Bending water using static electricity

This experiment requires only a comb and a thin stream of water.

If your faucet can create a thin stream of water you can perform this experiment at the faucet. If it doesn’t, fill a plastic bottle with some water and pierce a tiny hole on the bottom of the bottle, this will create a thin stream of flowing water.

Once you have a thin stream of water, run the comb through your hair quickly. The more you run it through, the stronger the charge on the comb will be. Now bring the comb closer to the stream and watch as the stream of water bends toward the comb.

This whole experiment is possible due to the presence of static electricity (the accumulation of charge on an object). When objects are rubbed together electrons hop from one object onto the other. The object that gains electrons becomes negatively charged and the one that loses electrons becomes positively charged.

When a charged object is brought close to another object it attracts the new object, this is how the comb attracts water.

Tip: It’s easier to produce static electricity in low humidity environments. Humidity causes a layer of moisture to be formed on surfaces which prevent electrons from transferring between objects.

There’s a great video from ‘Jefferson Labs’ that demonstrates this experiment:

Create your own air pump to fill a balloon

This project requires the assistance of an adult.

You will need an empty bottle, 2 balloons, tape, a rubber band, and a blade or scissors (that must be handled only by an adult).

First, ask an adult to make a rectangular slit at the centre of the bottle cap using the blade.

Then cut one balloon to obtain a rectangular piece that is slightly larger than the slit on the cap.

Place the rectangular balloon piece over the slit (on the exterior side of the cap) and use the tape to seal 3 sides of the balloon onto the slit, leaving only one side of the balloon piece open.

Now, cut a circle (about 1 centimetre in diameter) on the body of the empty bottle.

Attach the cap back onto the bottle and place the second balloon over the cap of the bottle such that the mouth of the balloon is wrapped around the cap. Use the rubber band to keep the balloon in place.

The setup is complete, squeeze the bottle in quick successions with your finger placed over the hole you cut in the bottle. The balloon will fill up but will not deflate when you stop squeezing the bottle.

The air inside the balloon will apply pressure on the balloon piece and keep it closed, trapping the air in the balloon within the balloon.

That’s all there is to it, you’ve made your own air pump.

Here’s a video by NewKew that demonstrates this entire experiment:

Creating a bottle tornado

GIF by sundermier

For this experiment, you need two bottles of the same capacity and capsize, duct tape and water. You can also add food colouring or dyes to improve the appearance of the tornado.

First, fill up one bottle with water, if you’ve got any dyes add them to the water to improve visibility and make the tornado colourful.

Once the bottle is ready, use the duct tape to attach the empty bottle onto the full bottle such that the water flows from the full bottle into the empty bottle when the full bottle is placed upside down and no air can escape between the two bottles.

Now place the empty bottle on the table so that the full bottle is draining the water into the empty bottle. Quickly, give the full bottle a whirl so that the water spins as it drains but make sure you provide support to the duct-taped area while you do it. The water going out forces the air in the empty bottle to go into the full bottle through the centre, creating a vortex.

Hooray! You’ve just made your very own bottle tornado.

Making your own glass xylophone

All you need for this experiment are a few glasses, a spoon and water.

Fill the glasses with different quantities of water such that each glass contains a different level of water.

Now tap each glass lightly at the sides, do they all sound different?

If you look closely at the water after tapping a glass, you can see the vibrations on the water’s surface.

The working of the glass xylophone is based on the energy you provide to the glass and the water it contains when you tap it.

You might have noticed that the sound produced by glasses that contain very little water are almost similar, while the sound produced by glasses that are nearly full but differ by small quantities are more distinguishable. This is because when the glass is almost empty the pitch is high and when the glass is almost full the pitch is low, it is easier to distinguish a change in low pitches than it is to recognize a similar change in high pitches.

The pitch of the sound is determined by the frequency of the vibrations that cause the sound. In turn, the frequency of the vibration depends on the mass of the water in the glass. This is why different amounts of water produce different sounds.

You can keep altering the quantity of water in each glass until you’re satisfied with the sounds you can create or you can add more glasses with different quantities of water to increase the range of notes you can play.

With practice, you can play some really great tunes on a glass xylophone.
Here’s a tip: thinner walled glasses produce a nicer sound.

Here’s a video from ‘Cool Science Experiments Headquarters’ that demonstrates this experiment:

Creating and experimenting with Non-Newtonian fluids

The Non-Newtonian fluid we’re going to use is Oobleck, it’s fairly simple to make. Get 2 cups of cornstarch and mix it with 1 cup of water and that’s it. You’ve got Oobleck.

It’s sometimes not easy to get the ratio right so try mixing fresh batches a couple of times and you will have made your first non-Newtonian fluid.

The thing about non-Newtonian fluids is that its physical characteristics don’t depend on temperature but on pressure. If you hit the Oobleck quickly, it will feel like a solid. If you slide your hand into the Oobleck slowly, it will go right through.

Now punching Oobleck quickly and pushing through it slowly is an experiment by itself that demonstrates the varying viscosity of non-Newtonian fluids but if you’d like to see some other strange properties of this Non-Newtonian fluid you’re going to need a subwoofer and the help of your parents.

First, mix a nice batch of Oobleck, if it’s runny (or flowing) add more cornstarch and if it’s too hard, add more water. If it behaves like a solid when you punch it but allows your hand to go through it when you poke it slowly, you’ve got it just right.

Now, ask your parent to place the subwoofer on the ground with the woofer facing the ceiling. Place a thin metal tray or cookie sheet on the woofer. The goal is to pour the Oobleck onto the tray or sheet without allowing any of it to pass onto the subwoofer. The tray must, however, be thin enough to allow the vibrations from the subwoofer to move the Oobleck on the tray.

Ask your parents to play different frequencies on the subwoofer to find which one works best for the experiment. You can find audio tracks of different frequencies on YouTube.

Make sure to keep the Oobleck moving so it doesn’t solidify too much to move with the vibrations. When a frequency works for the experiment you should witness the Oobleck starting to rise and move almost like it’s a living being.

To make the experiment livelier and possibly prettier add a few drops of watercolours in different spots on the Oobleck and watch them mix by themselves as the Oobleck dances along with the vibrations.

Before you get rid of the Oobleck in the drain, add plenty of water to and make it runny so that it doesn’t clog the drain at any point.

Here’s a video from the channel ‘Get Crafty Crafty’ showing you how to create Oobleck:

And here’s another video from ‘Explainer TV’ showing how Oobleck dances on a subwoofer: