Category Archives: Science Experiments

Chromatography – Black Ink

Chromatography – Black Ink

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srpchromsetupBlack ink is black, right? Today you are going to find out. In this experiment you will be able to see all of the dye colors that mix together to make black ink.

What You Need:

  • Paper Towel or Coffee Filter
  • Bowl
  • Water
  • Several different kinds of black markers

Cut strips from the paper towel about 1 inch wide – one for each type of srpchrombowlmarker. Scribble across the bottom of one of the paper towel strips with each kind of marker. Scribble about one inch from one end of the paper towel strip. Tape the OTHER end of the strip to the maker you used to scribble on that strip. That will help you remember which marker goes with each paper towel strip.

Now hang the paper towel strips above the bowl of water so that only a little bit of the scribble end is in the water. Do not submerge the pen scribbles! Check on the paper towels in an hour. What has happened to the pen marks?

What you see happening on the paper towel strips is called chromatography. The color srpchromstripsof the ink in markers is made by mixing different pigments together. A pigment is a substance that makes color, like ink or dye. To make black, several pigments are mixed together. When the end of the paper towel strip is submerged in water the water soaks up through the paper towel. When the water passes through the black ink marks it takes the pigment colors with it. Different colors of pigments travel with the water at different rates because the molecules of some pigments stick to the paper more strongly than others. So, as the water travels it separates the colors. This is called chromatography – separating the parts of a mixture so that you can see them one at a time. It looks like there is more than one way to make black!

Here are websites and books that will help you understand solutions and experiment with chromatography:

Mixtures and Solutions Chromatography (pages 34-38)

Mixtures and Solutions Mixing and Separating Mixtures and Solutions

Words to Know:

Chromatography - A process that separates a mixture by passing it through something that will separate its parts.
Mixture – A substance made by mixing two or more substances together. The molecules of the substances don’t join together so the substances can be easily separated.
Homogeneous Mixture – A type of mixture that is the same throughout. Salt water and ink are good examples.
Pigment - A substance used for coloring; ink, dye, etc.

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Center of Gravity – Fork on Glass; Balanced Pop Can

Center of Gravity – Fork on Glass; Balanced Pop Can

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Gravity is the force that pulls objects toward the center of the Earth. An object’s center of gravity is the average location of the weight of the object.

If you have a wooden ruler you can balance it on your finger at the 6 inch mark. The ruler has a uniform shape and it’s weight is evenly distributed along its shape. It is easy to determine that the 6 inch mark, right in the middle, is the center of gravity for the ruler. There is an equal amount of weight on each side of the 6 inch mark; the gravitational pull on both sides of the rule is equal – so the ruler will balance.

If you have an object like a person trying to balance on a balance beam, then it is a little trickier to figure out where the center of gravity is located. It will be a little different for each gymnast depending on how their weight is distributed on their body. Each gymnast learns the location of their own center of gravity and knows to keep that point centered over the balance beam. If that point is not centered, the gymnast will fall off.

In today’s experiments you will find the center of gravity for objects that are not as easy as a ruler, you will find the center of gravity for a pop can and a fork.

What You Need:

  • an Empty Soda Can

Here is a video that will show you exactly what to do to balance a pop can:

srpbalancecan

I tried the pop can and it really did work. It only took a couple tries too. It is a little harder to tap it and make it go in a circle.

Balancing the two forks is a little harder.

What You Need:

  • Two Identical Forks
  • Toothpicks
  • Salt Shaker
  • Empty Pop Can
  • Water

First, stick a toothpick in the center hole of a salt shaker. This will act as your balance point. Now take the two forks and press the tines of the two forks together, making them into an “L” shape. Hold a toothpick in your hand and try to balance the forks on the toothpick. Once you get the forks balanced, transfer them from the toothpick you are holding to the toothpick stuck in the salt shaker. The girl in the video makes it look easy. Not easy!

Here are some websites and books that will help you understand and play with gravity:

What holds us to earth?: a Look at Gravity Cool Gravity Activities Science Rocks Gizmos and Gadgets

Words to Know:

Gravity – The force that pulls everything toward the center of Earth; the force of gravitation on Earth.
Center of Gravity - The average location of the weight of an object.
Weight – A measure of the force of gravity upon an object
Balance – An even distribution of weight so that an object will remain upright and steady even if it is resting on a very small point.

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Newton’s Third Law of Motion

Newton’s Third Law of Motion

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Newton’s Third Law of Motion: For every action there is an equal and opposite re-action.

SIMPLY: If you push an object, that object pushes back in the opposite direction equally hard.

In this video, an astronomer demonstrates Newton’s Third Law of Motion:

Here are some websites to help you demonstrate and learn about Newton’s 3rd Law:

Gizmos and Gadgets – Action-Reaction Rocket (Pages 18-26)

Here are some books that will help you do some reseach for your experiment if you are doing it for the science fair.
Giants of Science: Isaac Newton Many Ways to Move Gizmos and Gadgets What are Newton's Laws of Motion?

Words to Know:

Newton’s Third Law of Motion – For every action there is an equal and opposite re-action.

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Newton’s Second Law of Motion – Comet Cratering

Newton’s Second Law of Motion – Comet Cratering

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Today’s experiment will demonstrate Newton’s Second Law of Motion.

Newton’s Second Law of Motion: Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).

SIMPLY: Pushing or pulling an object produces acceleration, a change in the speed of motion. Believe it or not, an accelertion can be a slowdown OR a speedup. The heavier the object, the more force it takes to make that object speed up or slow down. It takes more of your strength to push a bowling ball one foot than it does to push a marshmallow one foot.

In this video, an astronomer demonstrates Newton’s Second Law of Motion:

What You Need:srpcometsetup2

  • Pie Pan or Other Dish with Sides
  • Flour
  • Hot Chocolate Mix
  • 3 Sizes of Marbles or Rocks
  • Spoon

Put several spoonfuls of flour in the bottom of the pan and spread it out to make a level surface. Then sprinkle a thin layer of hot chocolate mix on top of the flour. Now hold one marble/rock above the surface of the flour and drop it. Do the same with the other two marbles/rocks. Now carefully lift each marble/rock out of the flour and look at the impact crater. Which marble/rock made the widest impact crater? Which one made the deepest impact crater?

srpcometflour srpcometchocolate srpcometthree

 

srpcometcrater srpcometcompare1

 

Science Project Idea:

Do this experiment again. Use three different sizes of marbles. Marbles are great for this project because they are round which makes measuring the size of the impact crater easier. Remember that in a science experiment you want to test only one variable. In this experiment we only want to change the size/weight of the object that is falling. If we changed the shape of the object too, it would be hard to measure the difference in the impact craters.

While doing the experiment, pay close attention to how far away the marbles are from the surface of the flour before you let go of them. Use a rule to make sure you drop each marble from exactly one foot above the surface of the flour. Do the experiment three times using the same three objects. The three times you repeat the experiment are called trials. Make a chart to keep track of the results. After each trial measure the width of the impact crater made by each of the three marbles. Which marble makes the largest impact crater? Which marble makes the deepest impact crater? Why do you think so?

Giants of Science: Isaac Newton Isaac Newton and Physics for Kids Gizmos and Gadgets Give It a Push Give It a Pull
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Inertia – Tablecloth Trick & Egg Drop

Inertia – Tablecloth Trick & Egg Drop

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Physicists study matter – all of the “stuff” in the universe and how that “stuff” moves. One of the most famous physicists of all time was Sir Isaac NewtonSir Isaac is most famous for explaining gravity, a concept we are so familiar with now it seems obvious to us. He is also famous for explaining how stuff moves, his Three Laws of Motion. Today we are going to look at Newton’s First Law of Motion called Inertia.

Newton’s First Law of Motion (Inertia): A still object will stay still unless a force pushes or pulls it. A moving object will stay moving unless a force pushes or pulls it.

Gravity and friction are forces that constantly push and pull the “stuff” on earth. So, when we roll a ball, it slowly comes to a stop. On the moon, where there is less gravity and friction, “stuff” floats, and keeps floating.

In this video, an astronomer demonstrates Inertia:

Here are some good websites that explain inertia or show you experiments to try:

You can try two Inertia Experiments at home: The Tablecloth Trick and The Egg Drop. The two videos will give you good directions.

For The Tablecloth Trick You Will Need:

Drinking Glasses (non-breakable!)
a Plate (non-breakable!)
a Piece of Frabric or Tablecloth with NO HEM
Water
a Table
The items on the tablecloth – the drinking glasses full of water and the plate – are not moving. According to Newton’s law they should stay still unless a force pushes or pulls them. When you pull the tablecloth out from under them friction is a force that causes the plate to move just a little, but since the cloth is slippery it pulls right out, leaving the plate and glasses full of water in place.

For The Egg Drop You Will Need:

Egg
Toilet Paper Tube
Pie Pan
Drinking Glass
Water

In The Egg Drop the egg is not in motion, it is at rest. According to Newton’s law it should stay that way. When you slap the pan away you apply force to the pan and it moves, knocking out the toilet paper tube also, but you did not hit the egg so it stays in place. It DOES drop though, since the support of the toilet paper tube is gone gravity acts on the egg and pulls it toward the earth.

In this video see how seat belts and head rests in cars help save lives by using Newton’s First Law of Motion (Inertia):

Here are some books that will help you understand inertia, learn about Sir Isaac Newton or get directions for inertia science experiments:

  • Gizmos and Gadgets – Inertia Zoom Ball (pages 9-10); Inertia Coin Magic (page 12).
  • Google Preview: Naked Eggs and Flying Potatoes: The Egg Drop  (Pages?)
Giants of Science: Isaac Newton Isaac Newton and Physics for Kids Naked Eggs and Flying Potatoes Gizmos and Gadgets

Words to Know:

Physics – The study of matter and motion.
Physicist – A person who studies matter and motion.
Sir Isaac Newton – A physicist from the 16/17th Century who figured out gravity and three laws of motion.
Laws of Motion – Rules that explain how matter, or “stuff” moves on earth.
Inertia – Newton’s First Law of Motion. Every object persists in its state of rest or uniform motion in a straight line unless it is compelled to change that state by forces impressed upon it. SIMPLY: A still object will stay still unless a force pushes or pulls it. A moving object will stay moving unless a force pushes or pulls it.

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