Fun Science Projects

Design and test a parachute

What you'll need:
A plastic bag or light material
Scissors
String
A small object to act as the weight, a little action figure would be perfect

Instructions:
Cut out a large square from your plastic bag or material.
Trim the edges so it looks like an octagon (an eight sided shape).
Cut a small whole near the edge of each side.
Attach 8 pieces of string of the same length to each of the holes.
Tie the pieces of string to the object you are using as a weight.
Use a chair or find a high spot to drop your parachute and test how well it worked, remember that you want it to drop as slow as possible.

What's happening?
Hopefully your parachute will descend slowly to the ground, giving your weight a comfortable landing. When you release the parachute the weight pulls down on the strings and opens up a large surface area of material that uses air resistance to slow it down. The larger the surface area the more air resistance and the slower the parachute will drop.
Cutting a small hole in the middle of the parachute will allow air to slowly pass through it rather than spilling out over one side, this should help the parachute fall straighter.

Warm air needs more room

What you'll need:
Empty bottle
Balloon
Pot of hot water (not boiling)

Instructions:
Stretch the balloon over the mouth of the empty bottle.
Put the bottle in the pot of hot water, let it stand for a few minutes and watch what happens.

What's happening?
As the air inside the balloon heats up it starts to expand. The molecules begin to move faster and further apart from each other. This is what makes the balloon stretch. There is still the same amount of air inside the balloon and bottle, it has just expanded as it heats up.
Warm air therefore takes up more space than the same amount of cold air, it also weighs less than cold air occupying the same space. You might have seen this principle in action if you've flown in or watched a hot air balloon.


Make an egg float in salt water

What you'll need:
One egg
Water
Salt
A tall drinking glass

Instructions:
Pour water into the glass until it is about half full.
Stir in lots of salt (about 6 tablespoons).
Carefully pour in plain water until the glass is nearly full (be careful to not disturb or mix the salty water with the plain water).
Gently lower the egg into the water and watch what happens.

What's happening?
Salt water is denser than ordinary tap water, the denser the liquid the easier it is for an object to float in it. When you lower the egg into the liquid it drops through the normal tap water until it reaches the salty water, at this point the water is dense enough for the egg to float. If you were careful when you added the tap water to the salt water, they will not have mixed, enabling the egg to amazingly float in the middle of the glass.

Diet Coke eruptions with Mentos

What you'll need:
Large bottle of Diet Coke
About half a pack of Mentos
Geyser tube (optional but makes things much easier)

Instructions:
Make sure you are doing this experiment in a place where you won't get in trouble for getting Diet Coke everywhere. Outside on some grass is perfect, please don't try this one in your family lounge!!
Stand the Diet Coke upright and unscrew the lid. Put some sort of funnel or tube on top of it so you can drop the Mentos in at the same time (about half the pack is a good amount). Doing this part can be tricky if you don't have a specially designed geyser tube, I recommend buying one from a local store such as Natures Discoveries (NZ) or online.
Time for the fun part, drop the Mentos into the Diet Coke and run like mad! If you've done it properly a huge geyser of Diet Coke should come flying out of the bottle, it's a very impressive sight. The record is about 9 metres (29 feet) high!

What's happening?

Although there are a few different theories around about how this experiment works, the most favoured reason is because of the combination of carbon dioxide in the Diet Coke and the little dimples found on Mentos candy pieces.

The thing that makes soda drinks bubbly is the carbon dioxide that is pumped in when they bottle the drink at the factory. It doesn't get released from the liquid until you pour it into a glass and drink it, some also gets released when you open the lid (more if you shake it up beforehand). This means that there is a whole lot of carbon dioxide gas just waiting to escape the liquid in the form of bubbles.
Dropping something into the Diet Coke speeds up this process by both breaking the surface tension of the liquid and also allowing bubbles to form on the surface area of the Mentos. Mentos candy pieces are covered in tiny dimples (a bit like a golf ball), which dramatically increases the surface area and allows a huge amount of bubbles to form.

The experiment works better with Diet Coke than other sodas due to its slightly different ingredients and the fact that it isn't so sticky. I also found that Diet Coke that had been bottled more recently worked better than older bottles that might have lost some of their fizz sitting on shop shelves for too long, just check the bottle for the date.

Make a ping pong ball float

What you'll need:

At least 1 ping pong ball (2 or 3 would be great)
A hair dryer
Instructions:

Plug in the hair dryer and turn it on.
Put it on the highest setting and point it straight up.
Place your ping pong ball above the hair dryer and watch what happens.
What's happening?

Your ping pong ball floats gently above the hair dryer without shifting sideways or flying across the other side of the room. The airflow from the hair dryer pushes the ping pong ball upwards until its upward force equals the force of gravity pushing down on it. When it reaches this point it gently bounces around, floating where the upward and downward forces are equal.

The reason the ping pong ball stays nicely inside the column of air produced by the hair dryer without shifting sideways is due to air pressure. The fast moving air from the hair dryer creates a column of lower air pressure, the surrounding higher air pressure forces the ping pong ball to stay inside this column, making it easy to move the hair dryer around without losing control of the ping pong ball.

See if you can float 2 or even 3 ping pong balls as an extra challenge.


Invisible Ink with Lemon Juice

What you'll need:

Half a lemon
Water
Spoon
Bowl
Cotton bud
White paper
Lamp or other light bulb
Instructions:

Squeeze some lemon juice into the bowl and add a few drops of water.
Mix the water and lemon juice with the spoon.
Dip the cotton bud into the mixture and write a message onto the white paper.
Wait for the juice to dry so it becomes completely invisible.
When you are ready to read your secret message or show it to someone else, heat the paper by holding it close to a light bulb.
What's happening?

Lemon juice is an organic substance that oxidizes and turns brown when heated. Diluting the lemon juice in water makes it very hard to notice when you apply it the paper, no one will be aware of its presence until it is heated and the secret message is revealed. Other substances which work in the same way include orange juice, honey, milk, onion juice, vinegar and wine. Invisible ink can also be made using chemical reactions or by viewing certain liquids under ultraviolet (UV) light.


Blowing Up Balloons With CO2

What you'll need:

Balloon
About 40 ml of water (a cup is about 250 ml so you don't need much)
Soft drink bottle
Drinking straw
Juice from a lemon
1 teaspoon of baking soda
Instructions:

Before you begin, make sure that you stretch out the balloon to make it as easy as possible to inflate.
Pour the 40 ml of water into the soft drink bottle.
Add the teaspoon of baking soda and stir it around with the straw until it has dissolved.
Pour the lemon juice in and quickly put the stretched balloon over the mouth of the bottle.
What's happening?

If all goes well then your balloon should inflate! Adding the lemon juice to the baking soda creates a chemical reaction. The baking soda is a base, while the lemon juice is an acid, when the two combine they create carbon dioxide (CO2). The gas rises up and escapes through the soft drink bottle, it doesn't however escape the balloon, pushing it outwards and blowing it up. If you don't have any lemons then you can substitute the lemon juice for vinegar.

Experience Gravity Free Water

What you'll need:

A glass filled right to the top with water
A piece of cardboard
Instructions:

Put the cardboard over the mouth of the glass, making sure that no air bubbles enter the glass as you hold onto the cardboard.
Turn the glass upside down (over a sink or outside until you get good).
Take away your hand holding the cardboard.
What's happening?

If all goes to plan then the cardboard and water should stay put. Even though the cup of water is upside down the water stays in place, defying gravity! So why is this happening? With no air inside the glass, the air pressure from outside the glass is greater than the pressure of the water inside the glass. The extra air pressure manages to hold the cardboard in place, keeping you dry and your water where it should be, inside the glass.


Making Music with Glasses of Water

What you'll need:

5 or more drinking glasses or glass bottles
Water
Wooden stick such as a pencil
Instructions:

Line the glasses up next to each other and fill them with different amounts of water. The first should have just a little water while the last should almost full, the ones in between should have slightly more than the last.
Hit the glass with the least amount of water and observe the sound, then hit the glass with the most water, which makes the higher sound?
Hit the other glasses and see what noise they make, see if you can get a tune going by hitting the glasses in a certain order.
What's happening?

Each of the glasses will have a different tone when hit with the pencil, the glass with the most water will have the lowest tone while the glass with the least water will have the highest. Small vibrations are made when you hit the glass, this creates sound waves which travel through the water. More water means slower vibrations and a deeper tone.



Mixing Oil & Water

What you'll need:

Small soft drink bottle
Water
Food colouring
2 tablespoons of cooking oil
Instructions:

Add a few drops of food colouring to the water.
Pour about 2 tablespoons of the coloured water along with the 2 tablespoons of cooking oil into the small soft drink bottle.
Screw the lid on tight and shake the bottle as hard as you can.
Put the bottle back down and have a look, it may have seemed as though the liquids were mixing together but the oil will float back to the top.
What's happening?

While water often mixes with other liquids to form solutions, oil and water does not. Water molecules are strongly attracted to each other, this is the same for oil, because they are more attracted to their own molecules they just don't mix together. They separate and the oil floats above the water because it has a lower density.

If you really think oil and water belong together then try adding some dish washing liquid or detergent. Detergent is attracted to both water and oil helping them all join together and form something called an emulsion. This is extra handy when washing those greasy dishes, the detergent takes the oil and grime off the plates and into the water, yay!

Crazy Putty

What you'll need:

2 containers (1 smaller than the other, preferably a film canister)
Water
Food colouring
PVA glue
Borax solution (ratio of about 1 Tbsp of borax to a cup of water)
Instructions:

Fill the bottom of the larger container with PVA glue.
Add a few squirts of water and stir.
Add 2 or 3 drops of food colouring and stir.
Add a squirt of borax (possibly a bit more depending on how much PVA glue you used).
Stir the mixture up and put it into the smaller container. By now the mixture should be joining together, acting like putty, crazy putty!
What's happening?

The PVA glue you use is a type of polymer called polyvinyl acetate (PVA for short), while the borax is made of a chemical called sodium borate. When you combine the two in a water solution, the borax reacts with the glue molecules, joining them together into one giant molecule. This new compound is able to absorb large amounts of water, producing a putty like substance which you can squish in your hands or even bounce.


Bend A Straw With Your Eyes

What you'll need:

A glass half filled with water
A straw
2 eyes (preferably yours)
Instructions:

Look at the straw from the top and bottom of the glass.
Look at the straw from the side of the glass, focus on the point where the straw enters the water, what is strange about what you see?
What's happening?

Our eyes are using light to see various objects all the time, but when this light travels through different mediums (such as water & air) it changes direction slightly. Light refracts (or bends) when it passes from water to air. The straw looks bent because you are seeing the bottom part through the water and air but the top part through the air only. Air has a refractive index of around 1.0003 while water has a refractive index of about 1.33.

Water on the move

What you'll need:

A glass of water
An empty glass
Some paper towels
Instructions:

Twist a couple of pieces of paper towel together until it forms something that looks a little like a piece of rope, this will be the 'wick' that will absorb and transfer the water (a bit like the wick on a candle transferring the wax to the flame).
Place one end of the paper towels into the glass filled with water and the other into the empty glass.
Watch what happens (this experiment takes a little bit of patience).
What's happening?

Your paper towel rope (or wick) starts getting wet, after a few minutes you will notice that the empty glass is starting to fill with water, it keeps filling until there is an even amount of water in each glass, how does this happen?

This process is called 'capillary action', the water uses this process to move along the tiny gaps in the fibre of the paper towels. It occurs due to the adhesive force between the water and the paper towel being stronger than the cohesive forces inside the water itself. This process can also be seen in plants where moisture travels from the roots to the rest of the plant.

Is this egg hard boiled or raw?

What you'll need:

Two eggs, one hard boiled and one raw. Make sure the hard boiled egg has been in the fridge long enough to be the same temperature as the raw egg.
Instructions:

Spin the eggs and watch what happens, one egg should spin while the other wobbles.
You can also lightly touch each of the eggs while they are spinning, one should stop quickly while the other keeps moving after you have touched it.
What's happening?

The raw egg's centre of gravity changes as the white and yolk move around inside the shell, causing the wobbling motion. Even after you touch the shell it continues moving. This is because of inertia, the same type of force you feel when you change direction or stop suddenly in a car, your body wants to move one way while the car wants to do something different. Inertia causes the raw egg to spin even after you have stopped it, this contrasts with the solid white and yolk of the hard boiled egg, it responds much quicker if you touch it.

This is a good experiment to test a friend or someone in your family with, see if they can figure out how to tell the difference between the eggs (without smashing them of course) before showing them your nifty trick.

What absorbs more heat?

What you'll need:

2 identical drinking glasses or jars
Water
Thermometer
2 elastic bands or some sellotape
White paper
Black paper
Instructions:

Wrap the white paper around one of the glasses using an elastic band or sellotape to hold it on.
Do the same with the black paper and the other glass.
Fill the glasses with the exact same amount of water.
Leave the glasses out in the sun for a couple of hours before returning to measure the temperature of the water in each.
What's happening?

Dark surfaces such as the black paper absorb more light and heat than the lighter ones such as the white paper. After measuring the temperatures of the water, the glass with the black paper around it should be hotter than the other. Lighter surfaces reflect more light, that's why people where lighter colored clothes in the summer, it keeps them cooler.

Use a balloon to amplify sound

What you'll need:

Balloon
Instructions:

Blow up the balloon.
Hold the balloon close to your ear while you tap lightly on the other side.
What's happening?

Despite you only tapping lightly on the balloon your ears can hear the noise loudly. When you blew up the balloon you forced the air molecules inside the balloon closer to each other. Because the air molecules inside the balloon are closer together, they become a better conductor of sound waves than the ordinary air around you.

Energy transfer through balls

What you'll need:

A large, heavy ball such as a basketball or soccer ball
A smaller, light ball such as a tennis ball or inflatable rubber ball
Instructions:

Make sure you're outside with plenty of room.
Carefully put the tennis ball on top of the basketball, holding one hand under the basketball and the other on top of the tennis ball.
Let go of both the balls at exactly the same time and observe what happens.
What's happening?

If you dropped the balls at the same time, the tennis ball should bounce off the basketball and fly high into the air. The two balls hit each other just after they hit the ground, a lot of the kinetic energy in the larger basketball is transferred through to the smaller tennis ball, sending it high into the air.

While you held the balls in the air before dropping them they had another type of energy called 'potential energy', the balls gained this through the effort it took you to lift the balls up, it is interesting to note that energy is never lost, only transferred into other kinds of energy.

Making Lemonade Fizzy Drink

What you'll need:

Lemon
Drinking glass
Water
1 teaspoon of baking soda
Some sugar to make it sweet
Instructions:

Squeeze as much of the juice from the lemon as you can into the glass.
Pour in an equal amount of water as lemon juice.
Stir in the teaspoon of baking soda.
Give the mixture a taste and add in some sugar if you think it needs to be sweeter.
What's happening?

The mixture you created should go bubbly and taste like a lemonade, soda, fizzy or soft drink, if you added some sugar it might even taste like a lemon flavoured soft drink you've bought at a store. The bubbles that form when you add the baking soda to the lemon mixture are carbon dioxide (CO2), these are the same bubbles you'll find in proper fizzy drinks. Of course they add a few other flavored sweeteners but it's not much different to what you made. If you are wondering how the carbon dioxide bubbles formed, it was because you created a chemical reaction when you added the lemon (an acid) to the baking soda (a base).

Dissolving sugar at different heats

What you'll need:

Sugar cubes
Cold water in a clear glass
Hot water in a clear glass (be careful with the hot water)
Spoon for stirring
Instructions:

Make sure the glasses have an equal amount of water.
Put a sugar cube into the cold water and stir with the spoon until the sugar disappears. Repeat this process (remembering to count the amount of sugar cubes you put into the water) until the sugar stops dissolving, you are at this point when sugar starts to gather on the bottom of the glass rather than dissolving.
Write down how many sugar cubes you could dissolve in the cold water.
Repeat the same process for the hot water, compare the number of sugar cubes dissolved in each liquid, which dissolved more?
What's happening?

The cold water isn't able to dissolve as much sugar as the hot water, but why? Another name for the liquids inside the cups is a 'solution', when this solution can no longer dissolve sugar it becomes a 'saturated solution', this means that sugar starts forming on the bottom of the cup.

The reason the hot water dissolves more is because it has faster moving molecules which are spread further apart than the molecules in the cold water. With bigger gaps between the molecules in the hot water, more sugar molecules can fit in between