Author: Maddie Van Beek

Happy Halloween!!!

A few weeks ago, we used candy for a chromatography experiment. This week, we are using simple potatoes to create magic goop that’s fun to play with! This would be a great Halloween activity. The magic mud that you’ll be creating behaves similarly to the slime you concocted in an earlier post. If you missed this fun and messy experiment, check it out here: http://discoveryexpress.weebly.com/blog/two-times-the-slime-fun-with-polymers.


This weird slimy substance that you’re working with today is a non-newtonian fluid. Non-newtonian fluids behave very differently from normal liquids or solids. Instead, they sometimes behave like a liquid and sometimes behave like a solid. When you apply pressure to a non-newtonian fluid, it resists and behaves like a solid. As soon as you release the pressure, the fluid returns to liquid form.

Although many people have experienced creating non-newtonian goop with corn starch, the magic mud you’re creating today behaves in the same way. How will you create the same kind of substance with a potato? Potatoes actually contain starch. You will have to first remove the starch from the potatoes to create your magic mud.

​Here's a video example of what you will be doing:

Below is a picture of what starch looks like. Starch is part of many foods including potatoes and is the most common carbohydrate in the human diet.

YOU WILL NEED:
* Bag of potatoes
* Water
* Food processor (optional)
* Knife (if food processor is not an option)
* Saucepan
* Kettle
* Strainer
* Jar


Here’s what to do!


1. Find an adult to help you with this activity! You may need to use a knife and you will use the stove, so make sure to be work carefully!

2. Wash a bag of potatoes in the sink.

3. Put your potatoes in the food processor and grind them into small pieces, or have an adult help you chop the potatoes into tiny pieces with a knife.

4. Dump the chopped-up potatoes into a mixing bowl.

5. Heat about 6 cups of hot water in the microwave or on the stove.

6. Carefully dump the hot water over the potato bits in the mixing bowl.

7. Stir the potatoes for a few minutes. What do you notice happening as you stir? The water actually changes color.

8. After about two minutes, place a strainer over an empty clear mixing bowl. Pour the potato water through the strainer to separate the liquid from the potato bits. Pay close attention to the liquid in the mixing bowl! What do you see happening? After 10 minutes, the liquid separates into two layers. The bottom of the bowl is white, while the reddish-brown liquid stays on the top. The white stuff you’ve removed from the potatoes is the potato starch. The starch is the necessary ingredient in making your non-Newtonian magic mud.

9. When this separation has happened, dump the top layer of liquid into the dirty mixing bowl. You should be left with just some white goop. The white goop looks a little dirty, so we are going to separate it even further.

10. Stir in about a cup of fresh water with the goop and pour it into a clear jar. Shake it up for 30 seconds and then let the jar sit for 10 minutes. You should notice that, once again, the liquid separates into two layers. The impurities stay on the top while the white goop sinks to the bottom.

11. Dump out the top layer of liquid. This should remove the impurities. You’re left with a milky-white substance. What does this substance feel like? Play with it! What do you notice about it? How does it act when you apply pressure? Try to roll it into a ball. What happens when you stop rolling? You’ll notice that when you stir it or roll it, the substance seems more firm, but when you stop applying pressure, it looks more like a liquid.


Extension:
Now that you’ve created your magic mud, go one step further and make it glow!


YOU WILL NEED:
* Fork
* Tonic water
* Black light


Here’s what to do!


1. Leave your magic mud in the jar for at least 24 hours. It will harden from a goopy slime into a solid.

2. Before you recreate your magic mud, take a look at your tonic water under a black light. Turn the black light on and the lights in the room off. What do you notice about the tonic water? It should be a glowing blue! The reason the tonic water is fluorescent under black lights is because of the ingredient quinine. (Don’t worry, the quinine in the tonic water is totally safe and non-toxic.)

Fluorescent objects absorb ultraviolet light that we can’t see, but they emit light than we can see. Read more here: http://www.scientificamerican.com/article/shining-science-explore-glow-in-the-dark-water/

The quinine in tonic water causes it to glow under a black light, so anything you mix with tonic water will also fluoresce! We are going to use tonic water to make your magic mud fluorescent. Turn the lights back on and let’s get going!

3. Use a fork to break up the solidified magic mud. It will easily crumble into a white powder.

4. Carefully add tonic water into the white powder. Add small amounts at a time and stir until the powder returns to its former goopy consistency.

5. Play with your new goop. What do you notice? It should behave exactly as it did before you let it dry. Here’s the big difference: When you turn on a black light, your magic mud will now eerily glow blue! For more fluorescent fun: Remember when we used tonic water to concoct glowing beverages for Halloween? Check it out here: http://discoveryexpress.weebly.com/blog/halloween-science).



Image and video credits:
Ord, 2003. Jack-'o-lantern 2003-10-31. Image uploaded from Wikimedia Commons on 10/30/2016. https://upload.wikimedia.org/wikipedia/commons/thumb/a/a2/Jack-o%27-Lantern_2003-10-31.jpg/800px-Jack-o%27-Lantern_2003-10-31.jpg File used in accordance with Creative Commons 2.5 License. Image was not changed.

Thompson, 2014. How to make magic mud - From a potato! Video uploaded from YouTube on 10/30/2016. https://youtu.be/_0J4dRqg7CE

Kalaya, 2009. Cornstarch mixed with water. Image uploaded from Wikimedia Commons on 10/30/2016. 
https://upload.wikimedia.org/wikipedia/commons/thumb/d/d5/Cornstarch_mixed_with_water.jpg/1024px-Cornstarch_mixed_with_water.jpg File used in accordance with Creative Commons 3.0 License. Image was not changed.

Author: Maddie Van Beek

Halloween is only a few weeks away! That means it's time for some spooky fun with Halloween science activities! 


1. Use your colorful candy to try out candy chromatography! 


What exactly is chromatography? 


Chroma means color and graphein means to write. 


There are a few different kinds of chromatography, but today you are going to be dealing with paper chromatography. When you use paper chromatography, you can separate different inks or dyes into their individual components. For example, a black marker actually has many different colors of dye to create black ink.

​Watch the video below to watch how paper chromatography can be used to separate black ink into its individual colors:

You can use this same idea to separate the dyes of your favorite candies! 


YOU WILL NEED

• M&Ms or Skittles
• Coffee filter paper
• A tall glass 
• Water 
• Table salt 
• Pencil
• Scissors
• Ruler 
• 6 toothpicks 
• Aluminum foil 
• 2 liter bottle with cap

Check out our blog about candy chromatography here for instructions:

2. Create your own glowing beverages! 


Did you know that tonic water glows under a black light? The reason that it does this is because of one special ingredient: quinine. 


Why is quinine fluorescent? Read the link below to find out! ​

Now that you know about quinine, do you know what a black light is? Why is a black light any different from a regular light? They might appear the same as any other light bulb, but they function very differently. Black lights actually produce ultraviolet light. When you turn a black light on, it causes white things to glow in the dark. 


Read about black lights in the link below to find out how they work: ​

YOU WILL NEED

• Tonic water
• Ice cube trays
• Sprite or 7-up
• A black light

​
Here’s what to do! 


The instructions for this activity are very simple. Make ice cubes out of tonic water and then put them in any light colored drink such as 7-up or Sprite. Turn on a black light, turn off the lights, and watch your beverages glow an eery blue!

​
3. Make pumpkin slime!


The slime that you will be creating is a non-newtonian fluid. Newtonian fluids behave as you would expect a liquid to behave. For example, when you hit water, it gives way. You can easily put your hand through it without much resistance. Non-newtonian fluids sometimes act like a solid and sometimes act like a liquid. When you hit a non-newtonian fluid, it resists the impact. How can that be? 


Watch this video to see people experiment with non-newtonian fluid. They even try to bike across it! You’ll be amazed at its power to resist stress. 

YOU WILL NEED:

• One pumpkin
• Cornstarch 
• Mixing bowl
• Spoon
• Cookie sheet or pan
• Food coloring (optional: your pumpkin will already color your slime an orangey tint)

Check out our blog from a few weeks ago to learn more about non-newtonian fluids and create your own pumpkin slime:

References:
https://sciencebob.com/free-halloween-science-ideas/

http://www.scientificamerican.com/article/shining-science-explore-glow-in-the-dark-water/
​
http://science.howstuffworks.com/innovation/everyday-innovations/black-light.htm

Image and video credits, in order of appearance: 

Amos, E., 2010. Plain-M&Ms-Pile. File uploaded from Wikimedia Commons on 10/9/2016.
https://upload.wikimedia.org/wikipedia/commons/thumb/e/e5/Plain-M%26Ms-Pile.jpg/800px-Plain-M%26Ms-Pile.jpg Image released into the Public Domain. 

Pauller, N., 2014. Paper chromatography - Chemistry experiment with Mr Pauller. Video uploaded from YouTube on 10/9/2016. ​https://youtu.be/ZCzgQXGz9Tg

Hard Science, 2013. Biking across a pool of corn starch - Hard science. Video uploaded from YouTube on 10/9/2016. ​https://www.youtube.com/watch?v=BleCJJAKkgw&feature=youtu.be

Author: Maddie Van Beek

It’s October--the leaves are changing colors, the weather is getting cooler, and you are probably starting to see all kinds of gourds and pumpkins at the grocery store. These days, people seem to like pumpkin flavored ANYTHING. Today, we aren’t going to eat any pumpkin, but we ARE going to use a pumpkin in our science activity to create PUMPKIN SLIME!

Last year, we showed you how to create two different kinds of slime. If you missed it, check it out here: http://discoveryexpress.weebly.com/homeblog/two-times-the-slime-fun-with-polymers

When we create pumpkin slime, we are going to follow similar instructions for the first version of slime that we concocted. In this version, the special ingredient for creating slime is cornstarch. 

The slime that you will be making is called a non-newtonian fluid. Newtonian fluids, such as water, do not provide much resistance when stress is applied to them. If you jump in a pool, the water gives way. Non-newtonian fluids change their viscosity or “flow behavior,” when stress or pressure is applied to them. Simply put, this means that the slime acts like both a liquid and a solid. When you poke it or pick it up and roll it into a ball, it feels like a solid. When you stop playing with it, it runs through your fingers like a liquid. Can you think of other substances that might sometimes act like a liquid and sometimes like a solid? 

Check out this video about non-newtonian fluids to see them in action!

Here’s more information about non-newtonian fluids: http://sciencelearn.org.nz/Science-Stories/Strange-Liquids/Non-Newtonian-fluids

According to the link you just read, what other substances besides slime or “oobleck” are non-newtonian fluids? Can you think of any others?

Now that you know a little bit about the science behind the slime, let’s get started!

YOU WILL NEED:

• One pumpkin
• Cornstarch 
• Mixing bowl
• Spoon
• Cookie sheet or pan
• Food coloring (optional: your pumpkin will already color your slime an orangey tint)

Here’s what to do!

1. Cut the pumpkin in half and clean out the guts and seeds with your hands or a spoon. Put all the pumpkin innards into a mixing bowl. How do the guts feel? Look? Write down your observations.

2. Pour 1/2 cup of water into the mixing bowl and use the spoon to stir the water into the pumpkin guts. Write down your observations. How does adding water to the pumpkin change it? 

3. Measure 1 cup of cornstarch and pour it into the bowl with the pumpkin guts and mix with the spoon until well-blended. What does your mixture look like now? How has the consistency changed? Record your observations. 

4. Optional: add about six drops of food coloring and stir it in. 

5. Place the pumpkin half on a pan or cookie sheet with the hollow part facing upward (The pan is just to keep your play area clean).

6. Now that you have your pumpkin slime all ready to go, dump it back in the pumpkin half for goopy fall play! 

7. Have fun! Pick up your pumpkin slime and play with it! What does it feel like? Look like? Is this what you expected to happen? 


Extension: Try adjusting the amount of water, glue, or starch to see how it changes the quality of the slime.




References:

http://littlebinsforlittlehands.com/pumpkin-oobleck-science-sensory-play/

https://sciencebob.com/make-some-starch-slime-today/

https://sciencebob.com/make-some-starch-slime-today-method-2/

http://serc.carleton.edu/sp/mnstep/activities/35866.html

http://scifun.chem.wisc.edu/homeexpts/gluep.htm

https://en.wikipedia.org/wiki/Non-Newtonian_fluid

Image and video credits, in order of appearance: 

Moore, K.T., 2015. Silverman's Farm. File uploaded from Wikimedia Commons on 10/3/2016. 
https://upload.wikimedia.org/wikipedia/commons/thumb/a/a1/Silverman%27s_Farm.jpg/800px-Silverman%27s_Farm.jpg File used in accordance with the Creative Commons Attribution-Share Alike 4.0 International license. No changes were made.

The Discovery Slow Down, 2013. Non-Newtonian Liquid IN SLOW MOTION! Video uploaded from YouTube on 10/3/2016. https://youtu.be/G1Op_1yG6lQ

2009. Pumpkin2007. File uploaded from Wikimedia Commons on 10/3/2016. 
https://upload.wikimedia.org/wikipedia/en/d/d8/Pumpkin2007.jpg File released into Public Domain. 

BradBeattie, 2006. Pumpkin seeds in hand. File uploaded from Wikimedia Commons on 10/3/2016. 
https://upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Pumpkin_seeds_in_hand.jpg/800px-Pumpkin_seeds_in_hand.jpg File used in accordance with the Creative Commons Attribution-Share Alike 3.0 Unported license. No changes were made.

​

Author: Maddie Van Beek

Energy: What you get when you eat a whole bag of Skittles and six Mountain Dews? Not exactly. What IS energy? Let's find out! 

Ok, so what are the two main types of energy? Put them into your own words!

• Potential

• Kinetic

So remember, energy is never actually LOST--it is just transferred or converted into other TYPES of energy. To go a little further into what potential and kinetic energy actually are, let’s watch this video! It may be an old cartoon, but the reality of energy has not changed! ​

Examples of potential and kinetic energy: 

Dropping a ball (or anything, really!)

Stretching a rubber band or shooting an arrow: The farther I stretch the rubber band, the more potential energy it has. When I let go of the rubber band, the potential energy immediately transfers into kinetic energy. This concept is very similar to archery. The stretched bow is full of potential energy; when the string is released, the bow's potential energy transfers into the arrow's kinetic energy. 

A roller coaster: As the roller coaster car climbs upwards, it is gaining potential energy. At the top of the peak, potential energy is at its height. As soon as the car drops downwards, all that gained potential energy is converted to kinetic energy. Kinetic energy is at an all-time high at the very bottom of the drop, and then it begins to convert back to potential energy. Kinetic energy increases at the same rate that potential energy decreases. They are INVERSES of one another.

Still confused? Think again of a roller coaster. If the roller coaster starts at the top with 100 Joules (Joules are the units used to measure both kinetic and potential energy) of potential energy, the point at the end of drop would have 100 Joules of kinetic energy, because that’s when the roller coaster would be at its fastest. A moment later, when the roller coaster starts going up again, that kinetic energy goes down, and what increases? That’s right, potential energy. 

Take a moment to think of a few more examples. When have you seen potential energy? When have you seen kinetic energy? 

Let’s demonstrate this! 

YOU WILL NEED:

• Basketball
• Tennis ball
• Tape measure or yard stick

Hypothesize: Does the height from which a ball is dropped affect how high a ball will bounce? 

Here's what to do!

1. Use the tape measure or yard stick to measure three feet up from the ground. 
2. Lift the basketball to the three foot mark. 
3. Drop the ball and pay attention to how it bounced. Record the height. Do this three times and find the average height.
4. Now, measure five feet up from the ground. Repeat steps 1-3. 
5. Did the height from which the ball was dropped affect the height that the ball bounced? Explain. 

Now, we will do the same with a tennis ball.

Hypothesize: Does the size of the ball affect how high it will bounce? 

Repeat steps 1-5 with the tennis ball. 

Did you get the same results? Explain.

Let's try something new! First, hold the basketball. Next, hold the tennis ball in place directly on top of the basketball. Drop both balls at the same exact time and watch what happens! 

You should have seen the basketball hit the ground and the tennis ball hit the basketball, which then sends the tennis ball flying! When does the tennis ball bounce higher--on its own, or when it hits the basketball? Record your observations. 

Why did the basketball cause the tennis ball to come bouncing back up? Would this work the same way if you dropped the balls in the opposite order? If you’re not sure, try it out and see what happens!

Based on your previous observations, which ball has more kinetic energy, the tennis ball or the basketball? Why do you think this is? 


Force

When you dropped the tennis ball and the basketball, you saw two forces at work. First, both the tennis ball and the basketball had a force acting upon them--gravity. Second, when the basketball hit the ground, the energy from the impact was transferred to the tennis ball, creating contact force. 

What is force, you ask? Force is the push or pull of an object that happens when an interaction between two objects occur. Picture two vehicles crashing into each head on at the same speed. If one vehicle is a semi-truck and one is a Mini Cooper, which vehicle will have more force enacted upon it? Well, think of the tennis ball as the Mini Cooper and the basketball as the semi-truck. That’s just a start on understanding force and Newton’s Laws, but that's enough for now! 

Until next time--May the force be with you! 

References:
​
https://en.wikipedia.org/wiki/Forms_of_energy

http://www.sciencekids.co.nz/experiments/bouncingballs.html

http://www.physicsclassroom.com/class/newtlaws/Lesson-2/The-Meaning-of-Force

http://www.eschooltoday.com/energy/kinds-of-energy/what-is-kinetic-energy.html

Image and Video Credits, in order of appearance:

The Science Asylum, 2013. What is Energy REALLY?! Uploaded from YouTube on 9/4/2016. https://youtu.be/jCrOtF7T4HE

cassiw2, 2009. The story of potential and kinetic energy. Uploaded from YouTube on 9/4/2016. https://youtu.be/7K4V0NvUxRg

​Bartz & Maggs, 2007. Bouncing ball strobe edit. Uploaded from Wikimedia Commons on 9/4/2016. 
https://upload.wikimedia.org/wikipedia/commons/thumb/3/3c/Bouncing_ball_strobe_edit.jpg/1024px-Bouncing_ball_strobe_edit.jpg File used in accordance with the Creative Commons Attribution-Share Alike 3.0 Unported license. No changes were made. 

Psalter, 1324. Longbowmen. Uploaded from Wikimedia Commons on 9/4/2016.
https://upload.wikimedia.org/wikipedia/commons/a/a7/Longbowmen.jpg File released into the Public Domain. 

BrandonR, 2005. Wooden roller coaster txgi. 
https://upload.wikimedia.org/wikipedia/commons/3/30/Wooden_roller_coaster_txgi.jpg
​Uploaded from Wikimedia Commons on 9/4/2016. File used in accordance with the Creative Commons Attribution-Share Alike 3.0 Unported license. No changes were made. 

Utchay Endre, 2008. May the force be with you. https://youtu.be/vSJNeXrCbE4 Uploaded from YouTube on 9/4/2016. 

Author: Maddie Van Beek

Surface tension is a “contractive tendency of the surface of a liquid that allows it to resist an external force” (Wikipedia). These forces are a result of the hydrogen bonds water molecules form with each other (see our answer to “Why does ice float?")

Put the definition into your own words! What is surface tension?

Below, check out a water strider using surface tension to "walk on water." The surface of the water is like a thin membrane that resists the force of objects such as the water strider.

Check for understanding! 

• What are some other examples of times you have seen surface tension in action? 

• Why do water molecules at the surface create stronger bonds? 

• What is the surface tension of water? Does it ever change, and why? 

• What is the difference between cohesion and adhesion? 

• When you add soap to water, what happens to the surface tension? Hypothesize why this is.

Click HERE to learn more. 

Follow up question: 

• Why does the addition of soap cause the spring to sink? 

Let’s try out a similar experiment! 


YOU WILL NEED:

• Cup
• Water
• Paperclip
• A square of toilet paper

Extension Materials

• Soap
• Baby powder

YOU WILL DO: 

1. Fill the cup with water.
2. Hypothesize: Does a paperclip float or sink? 
3. Place the paperclip on the surface of the water. What happens? Record. 
4. Remove the paperclip from the cup. 
5. Gently place the square (or small piece of the square) of toilet paper on the surface of the water. 
6. Gently place the paperclip on the surface of the toilet paper. 
7. Watch what happens and record observations. How is this different than the first time you put the paperclip in the cup? Why is this? 
8. You should see the toilet paper absorb water and sink, leaving the paperclip “floating” at the surface!
9. What happens when you bend the paperclip? Do different shapes make any difference? 

Extension

1. Try what Physics Girl did in her experiment! Put a bit of hand soap on your finger and touch the surface of the water. What happens? Why is this? 
2. Next, hypothesize how many paperclips the surface of your cup of water can hold! 
3. We know that soap makes the surface tension weaker, but can anything make the surface tension stronger? Take a guess!
4. Sprinkle baby powder on the surface of your water, and try the paperclip experiment again. How many paperclips “floated” this time? 
5. Try out other liquids such as soda, milk, vegetable oil, vinegar... do you obtain the same results, or are they different? 

Resources

http://en.wikipedia.org/wiki/Surface_tension

http://hyperphysics.phy-astr.gsu.edu/hbase/surten.html

http://www.sciencebob.com/experiments/paperclip.php

http://www.exploratorium.edu/ronh/bubbles/soap.html

​Image and video credits in order of appearance:

Apel, 2006. Water beading on a leaf. Uploaded from Wikimedia Commons on 8/8/2016. https://en.wikipedia.org/wiki/Surface_tension#/media/File:Dew_2.jpg File used in accordance with the Creative Commons Attribution 2.5 Generic license. No changes were made. 

Booyabazooka, 2008. Diagram of the forces on molecules of a liquid. Uploaded from Wikimedia Commons on 8/8/2016. https://upload.wikimedia.org/wikipedia/commons/thumb/f/f9/Wassermolek%C3%BCleInTr%C3%B6pfchen.svg/300px-Wassermolek%C3%BCleInTr%C3%B6pfchen.svg.png 
File released into the Public Domain. 

Vickers, 2008. Water strider. Uploaded from Wikimedia Commons on 8/8/2016. 
https://upload.wikimedia.org/wikipedia/commons/thumb/2/2c/Water_strider.jpg/1280px-Water_strider.jpg File released into the Public Domain. 
​
Billerbeck, 2010. Water strider or water bug.
​Uploaded from Youtube on 8/8/2016. https://youtu.be/b9nxUtoH7to

Physicsgirl, 2012. Amusing surface tension experiment. Uploaded from Youtube on 8/8/2016.
https://youtu.be/2F64qh9qPAI

Armin Kubelbeck, 2007. A metal paperclip floats on water. Uploaded from Wikimedia Commons on 8/8/2016. 
https://upload.wikimedia.org/wikipedia/commons/thumb/9/9c/Surface_Tension_01.jpg/1024px-Surface_Tension_01.jpg File used in accordance with the Creative Commons Attribution-Share Alike 3.0 Unported license. No changes were made. 

Author: Maddie Van Beek

​Think back to a time that you’ve stood in a pool or a lake. When you look down, do your legs look like they normally do? No! Have you ever wondered why your legs look bent, or as if they are shorter? This weird effect is called refraction! 

Refraction happens when a wave travels from one medium to a second medium in which the wave travels at a different speed (the speed of light is only constant in a vacuum). For example, when light goes from traveling through the medium of air to the medium of water, the speed of the light slows down and the wavelength shortens (the frequency of the wave—that is, the number of times the wave repeats in a given time—remains the same). The amount of refracting that occurs depends on the index of refraction. We can calculate the index of refraction (n) by dividing the speed of light in a vacuum (c) by the speed of light in that specific medium (v). That is:

Index of refraction = vacuum/specific medium

n = c / v
For example, the speed of light is 299,792,458 meters per second, but is commonly denoted as c. Let’s try calculating the refractive index for a vacuum.

Index of Refraction (n) = c (the speed of light) / c (the speed of light)

Anything divided by itself equals 1. Therefore, the refractive index for a vacuum is 1.

Below, you can see that the all other mediums have a larger refractive index than in a vacuum. This is because the speed of light in any other medium will be slower than in a vacuum. Therefore, the index of refraction will usually be over 1. Negative refractive indexes are only achieved with synthetic materials that possess uncommon refractive properties.

References:

• http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/refr.html#c3
• http://en.wikipedia.org/wiki/Refraction
• http://teachinginroom6.blogspot.com/2012/04/light-refraction-fun-independent.html
• http://science.howstuffworks.com/nature/climate-weather/storms/rainbow1.htm

Image and Video Credits in order of appearance: 

Image 1: Bcrowell, 2014. Refraction-with-soda-straw-cropped. Uploaded from Wikimedia Commons on 7/31/2016. https://en.wikipedia.org/wiki/Refraction#/media/File:Refraction-with-soda-straw-cropped.jpg File used in accordance with the Creative Commons Attribution-Share Alike 3.0 Unported license.

Image 2: JrPol, 2015. Refraction in a glass of water. Uploaded from Wikimedia Commons on 7/31/2016. https://upload.wikimedia.org/wikipedia/commons/thumb/f/f1/R-DSC00449-WMC.jpg/800px-R-DSC00449-WMC.jpg File used in accordance with the Creative Commons Attribution-Share Alike 4.0 International license. No changes were made. 

​Home Science, 2014. Amazing water trick - Amazing science tricks using liquid. Uploaded from Youtube on 7/31/2016. https://youtu.be/G303o8pJzls

Image 3: Inaglory, 2007. An inferior mirage on the Mojave desert in spring. Uploaded from Wikimedia Commons on 7/31/2016. https://upload.wikimedia.org/wikipedia/commons/7/7c/Desertmirage.jpg File released into the Public Domain. 

Image 4: Сергей Banifacyj Морозов, 2008. Rainbow after the rain, Grodnow, Belarus. File uploaded from Wikimedia Commons on 7/31/2016.
https://upload.wikimedia.org/wikipedia/commons/thumb/f/f4/%D0%A0%D0%B0%D0%B4%D1%83%D0%B3%D0%B0_%D0%BD%D0%B0%D0%B4_%D0%93%D1%80%D0%BE%D0%B4%D0%BD%D0%BE.jpg/1280px-%D0%A0%D0%B0%D0%B4%D1%83%D0%B3%D0%B0_%D0%BD%D0%B0%D0%B4_%D0%93%D1%80%D0%BE%D0%B4%D0%BD%D0%BE.jpg File used in accordance with the Creative Commons Attribution-Share Alike 4.0 International license. No changes were made. 

Author: Maddie Van Beek

Today we are going to experiment with GRAVITY! Last week we learned about this mysterious force and tested a few different ways we could defy gravity. If you missed it, check it out here: http://www.discoveryexpresskids.com/blog/defying-gravity

Today, we are going to learn about AIR RESISTANCE.


As you know from last week, gravity is the force that pulls all objects towards the core of the Earth. It’s what causes anything that is dropped to fall to the floor, and it’s what keeps you and me from flying off the Earth as it spins on its axis at incredible rates! Every single object is pulled towards the Earth with the same amount of gravity. So in theory, every object should fall at the same speed, right? Let’s test it out.


Grab a rock and a piece of paper. First, drop the rock. Next, drop the paper. Did they both fall at the same pace? Why do you think the paper fell slower than the rock? Next, crumple the paper into a ball and drop it once again. What happened? You should have noticed that the crumpled paper falls faster than a flat piece of paper. What’s going on?


AIR RESISTANCE! The reason that some objects fall slower than others is that they encounter different amounts of air resistance. The amount of air resistance depends largely on the surface area of the object. If the surface area is larger, the air resistance is stronger. That’s why a flat piece of paper falls slower... it has a much larger surface area than a rock. When you crumpled the paper, you reduced the surface area, so it fell faster.


Every object that falls accelerates at approximately 10m/s/s, but at a certain point, that acceleration levels off. That point is called terminal velocity. Terminal velocity is the point at which air resistance balances out the force of gravity. When an object reaches terminal velocity, it quits accelerating and continues to fall at a steady speed.

In real life, you see air resistance at work when someone uses a parachute. Using a parachute drastically decreases your terminal velocity by increasing air resistance, allowing you to float safely to the ground. Check out this link for more details on how parachutes work:
http://www.explainthatstuff.com/how-parachutes-work.html


Your job today is to create a parachute that will allow an egg to float safely to the ground without breaking.

YOU WILL NEED:
* Eggs
* Tape
* Plastic
* Cellophane
* Tissue paper
* Paper
* Cardboard
* Scissors


Here’s what to do!
1. Design your parachute. Use your imagination! You can use whatever materials you want to design a parachute that you think will help keep your egg safe. Think back to the information you’ve learned. Larger surface area = more air resistance.
2. Once you’ve designed your parachute, start building!
3. Cut four strings of equal length and tape one end to each corner of your parachute.
4. Tape the other end of the four strings to your egg. Make sure to tape them securely so they stick to the egg!
5. Time for testing! Hold your parachute as high above your head as possible, then let it drop.
6. Check your egg! Did it survive? If not, back to the drawing board. Continue redesigning until you have a parachute that transports your egg safely to the ground.


Extension: Create other parachutes of different sizes (make sure to keep all other design aspects the same). Does the size affect how well the parachutes work? Time each parachute to see which one floats the ground fastest/slowest.


Extension: Design other parachutes of the same size but with different materials. Which materials work best? Why do you think this is?


References
​http://www.physicsclassroom.com/class/newtlaws/Lesson-3/Free-Fall-and-Air-Resistance http://www.science-sparks.com/2011/09/08/gravity-and-air-resistance/

Author: Maddie Van Beek

Gravity! We can't escape it. You've experienced gravity whenever you've dropped something, tripped and fell to the ground, or just stood in one place while the Earth spins at an incredible rate, yet you don't fly off! How does this work? The force of gravity pulls you, and everything else, towards the core of the Earth. Without it, we would just float off into space!

Does gravity only exist on Earth? Nope! Gravity is actually “the force of attraction between any two masses,” so it doesn’t just exist on Earth, and gravity doesn’t just exist between the Earth and other objects. Anything with mass has a gravitational pull. Mass stays the same wherever you go, but gravity is what gives you weight. The more mass an object has, the stronger the gravitational pull, the higher the weight. In the object below, you can see that the astronaut’s mass stays at 120kg whether he’s on Earth or the moon, but his weight changes due to the differences in gravitational pull.

Sir Isaac Newton was the scientist who first defined gravity. His Theory of Universal Gravitation stated that gravity is a force that acts on all objects, and has to do with both mass and distance. Gravitational pull is higher with larger masses and lower with smaller masses. If the two objects are closer, the gravitational pull is stronger. If the two objects are further away, the gravitational pull is weaker.


The law of gravitational force looks like this:


(G * m1 * m2) / d^2


G = Gravitational constant
m1 = First object
m2 = Second object
d = Distance between the centers of gravity of m1 and m2


Check out more about gravity here: http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question30.html


Here’s a great video explanation of what gravity is and what it does:

Can we ever defy the force of gravity? Think of a time when you should have fallen but didn't. Think of a roller coaster. People spin upside down without falling out. How is this possible? Can you think of any other examples?
​
Now that you know what gravity is and does, let’s try a few activities that demonstrate gravity and ways that we can defy it!

Magic paper clips
One way that we can defy gravity is through magnetism. In this experiment, you will see how objects that normally should fall the ground defy the laws of gravity.


YOU WILL NEED:
* Two rulers
* Three strong magnets
* Three paper clips
* Scissors
* String
* Tape
* Two glasses


Here’s a video preview of what you will be doing:

Here’s what to do!
1. Pick a paper clip up. What happens when you drop it? It falls to the floor.
2. Cut three pieces of string. Each should be the same length, about 6 inches.
3. Tie a piece of string to each paper clip.
4. Tie the other end of each string to a ruler. Make sure they are evenly spaced apart. What happens when you pick the ruler up? The paper clips should dangle below. If you tilt the ruler, what do the paper clips do? Notice that they all continue to point directly at the ground, no matter which way you tilt the ruler.
5. Tape three magnets to your second ruler. They should be equally spaced out and should align with the paper clips on your first ruler. For example, if you tied your paper clips at 2inches, 6inches, and 10inches on the first ruler, that’s where you should tape your magnets on the second ruler.
6. Set a glass (at least 7 inches tall) on each side of the first ruler.
7. Place the ruler with the magnets across the glasses with the magnets facing down.
8. Lift each paper clip towards the magnet. What happens? You should see all three paper clips floating in mid-air! Why is this happening? The magnets are attracting the metal paper clips, causing them to defy gravity!
9. Lift the ruler with the magnets. What happens to the paper clips? Without the magnetism pulling on them, they comply with the laws of gravity and crash back to the ground.


Anti-gravity water
In this experiment, you’ll see another way that we can defy gravity!


YOU WILL NEED:
* Glass
* Water
* Piece of cardboard


Here’s what to do!
1. Pour water into the glass all the way to the top. Make sure it’s right up to the rim.
2. Cut a square of cardboard big enough to cover the mouth of the glass.
3. Carefully place the cardboard over the mouth of the glass. Make sure there are no space for air or air bubbles in the glass!
4. Carry the glass to the sink with your hand over the cardboard. Flip the glass upside-down.
5. Remove your hand from the cardboard. What happens? The cardboard stays in place, keeping the water from falling out! Defying gravity!
6. Why does this happen? The air pressure outside the glass is greater than the pressure of the water inside the glass, so the cardboard stays in place.




References
http://coolcosmos.ipac.caltech.edu/ask/300-What-is-gravity-
http://www.turtlediary.com/kids-science-experiments/defying-gravity-experiment.html
http://buggyandbuddy.com/gravity/
http://science.howstuffworks.com/environmental/earth/geophysics/question2321.htm

Author: Maddie Van Beek

Today, we are exploring the concepts of levers and fulcrums. You are going to create a simple machine that contains both a lever and a fulcrum--a ping-pong ball launcher! Before we get started, you need to know a little bit about what a lever is and what a fulcrum is.


First of all, what is a simple machine?


Think about what a machine does. There are so many different machines out there, but the main purpose behind machines is that they make life easier for people. Simple machines make work (the force acting on an object in the direction of motion) easier for humans to complete.


A simple machine could be any of the following:


* Wheel and axle
* Lever
* Inclined plane
* Pulley
* Screw
* Wedge


Read more about the six simple machines that make work easier (http://www.livescience.com/49106-simple-machines.html).


The simple machine you’re creating today is a lever.


A lever contains both a beam and a fulcrum. The fulcrum is the pivot of the lever. Think about levers in your everyday life. When have you seen a lever? One example is a seesaw... the bench that the two people sit on is the beam, while the center piece holding the beam in place is the fulcrum.

Fulcrum: The point at which the lever rests, is supported, and pivots.


Lever: A bar or beam resting on a pivot. Pressure (force) is applied to one end to help move an object (load) on the other end.


Check out the diagram of a lever below. You can see the beam resting over a pivot, which is the fulcrum. When you think of the ping-pong ball launcher you are about to create, the force will be you pushing down on the lever, and the load will be the ping-pong ball.

Now that you know a little bit about levers, you can get started on creating your own!


YOU WILL NEED:
* Plastic cup
* Ping-pong balls
* Wooden yardstick
* Tape
* Variety of fulcrums (thick book, shoe box, coffee can, log, etc.)


Here’s what to do!
1. Tape a plastic cup to one end of the wooden yardstick. Make sure you use lots of tape so the cup stays put! Your finished product should look like the shape below. The base of the cup is taped down, and the mouth of the cup is facing up. This is your ping-pong launcher!

2. Select your first fulcrum.
3. Set your your ping-pong launcher over the top of the fulcrum. The launcher should lean to the side over the fulcrum like the shape below.

4. Place the ping-pong in the plastic cup on the lower end of the launcher. Make a prediction, how far do you think the ping-pong ball will fly?
5. Quickly press down on the top end of the launcher to send the ball flying! Use a tape measure to check how far the ping-pong ball traveled. Repeat this five times and record your results each time. After the fifth launch, find the average launch distance. Do this by following the formula below.


Launch 1 + Launch 2 + Launch 3 + Launch 4 + Launch 5 = Total launch distance


Total launch distance / Number of launches


Total / 5 = Average Launch distance


6. How might changing the position of the fulcrum change the launch distance? Try moving the fulcrum closer to the launch cup.

Repeat step 5. What did you notice about the launch distance?


7. Try moving the fulcrum further away from the launch cup. Repeat step 5. What happened this time?

8. Record your conclusion. Which position launched the ball the furthest?


Extension: Now that you know which position works best, try using different fulcrums! Do different sizes or shapes affect the launch distance? Repeat the activity with at least two other fulcrums to determine which works best.


References:
http://buggyandbuddy.com/science-kids-launching-ping-pong-ball-snowmen/
http://www.livescience.com/49106-simple-machines.html

Author: Maddie Van Beek

Last week, we talked about Newton’s Second Law of Motion and the week before, we talked about Newton’s First Law of Motion. If you missed these, check them out at http://discoveryexpress.weebly.com/homeblog/demonstrating-the-law-of-inertia and http://discoveryexpress.weebly.com/homeblog/newtons-second-law. 




RECAP




Newton’s First Law of Motion

An object in motion will stay in motion, or an object at rest will stay at rest, unless affected by an outside force.




Newton’s Second Law of Motion

The acceleration of an object--as produced by a net force--is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. F = m * a




Now that you have revisited Newton’s first two laws, let’s move on to our focus for today, Newton’s Third Law of Motion. 

Newton’s Third Law is concerned with forces acting in pairs. Remember, a force is a push or a pull that is enacted upon an object. Forces result from interactions between two objects. For every action force, there is a reaction force. 

Every action has an equal and opposite reaction. Every force is met with an opposing force of equal strength. For example, my coffee cup is exerting a force on my table, but my table is exerting that same force on my coffee cup. Let’s say that my coffee cup is exerting a force of 5 N (due to gravity). My coffee cup is not moving, so my table must be exerting an equal force of 5 N in the opposite direction. Because those forces are equal, my coffee cup stands still. 




Another example would be doing wall-sits. If you are sitting up against a wall, you are exerting a force on that wall. What if the wall were not exerting that same force back at you? You’d fall over! 




If you want even more information on Newton’s Third Law, check out this video from KhanAcademy: 

Practice: Click on the link below to practice identifying action/reaction pairs. 

Activity: Create your own balloon car! 




Now that you know Newton’s Third Law of Motion tells us that for every action, there is an equal and opposite reaction, you will create a visual that demonstrates that statement. You are going to be making a paper car that’s powered purely by the air of a balloon! 




Predict: How does this action/reaction pair relate to the demonstration you are about to create?

If you would like a visual demonstration of what you will be doing, watch this helpful Howcast video! 

YOU WILL NEED

• Paper
• Scissors
• Balloon
• Rubber band
• Tape
• Lifesavers
• 3 Straws
• Creativity and a sense of fun! 

Here’s what to do! 

1. Fold a standard piece paper in half, and then fold it in half again. 
2. When you open your piece of paper back up, you there should be fold lines that divide the paper into four sections. 
3. Cut down those lines so that you have four equal pieces of paper. 
4. Grab one of those pieces and two straws. 
5. Using tape, attach a straw to each of the short sides of the paper. Make sure the straws are centered so that the same amount of straw is hanging off the sheet of paper on either side. It should look something like this: 

6. The straws will be your axles. Next, you are going to add your wheels. 

7. Grab a lifesaver and put it onto the straw so the straw is going through the center hole of the candy. The lifesavers are going to be your wheels. 

8. In order to hold your wheels in place, wrap the tape around the straw on the outside of the lifesaver until it becomes thicker than the hole of the lifesaver so it won’t fall off the straw. Make sure your wheel can still spin! 

9. Repeat step 7 and 8 to create your other three wheels. 

10. Now you have the base of your car made. Use tape and your remaining paper to create walls for your car. Be creative! 

11. Now, you need a source of energy to make your car move. Put the mouth of the balloon over the one end of your remaining straw. Wrap the rubber band around the mouth of the balloon about five times. It needs to be tight enough so air cannot escape, but not so tight that it crushes the straw. To make sure the rubber band is tight enough, blow air into the straw to blow up the balloon and then place your finger over the mouth of the straw to hold the air in. Listen closely... is air escaping? If so, wrap the rubber band tighter. If not, you’re good to go! 

12. Now, you need to attach your balloon to the car. Tape the straw to the base of your car so that the balloon end is facing the front of your car and the straw end is hanging off the back. Picture your straw as an exhaust pipe. Once you secure the straw to your car, blow up the balloon by blowing into the straw and place your finger over the end of the straw to keep the air from escaping. 

13. Set your balloon car on a level surface and remove your finger from the straw. 

14. Zoom! Your balloon car is off! The air escaping the balloon is causing your car to move. For every action, there is an equal and opposite reaction.  

15. Extension: Experiment with different car designs to see how design affects the speed of your car. 



References

http://science.howstuffworks.com/innovation/scientific-experiments/newton-law-of-motion4.htm

https://www.khanacademy.org/science/physics/forces-newtons-laws/newtons-laws-of-motion/v/newton-s-third-law-of-motion

https://www.youtube.com/watch?v=5eirTBW0rpI

http://www.physicsclassroom.com/class/newtlaws/Lesson-4/Newton-s-Third-Law