Canada Science and Technology Museum Presents

The Canada Science and Technology Museum presents: Challenge of the day

Event: March Break Event title: Genius at Play Date: March 3 to 18, 2012

Draft Written by Catherine Emond, February 2012 Reviewed by Sandra Corbeil, March 2012 Reviewed by Mélanie Hall, March 2012

Challenge of the Day, March Break 2012, last updated on March 1, 2012 Page 1 of 7 OVERALL ACTIVITY OBJECTIVES Objectives:

1. Visitors will be introduced to challenges that use scientific concepts 2. Visitors will be amazed to realise that logic is as important as scientific knowledge to solve the challenges 3. Visitors will have fun taking on the challenges

Outline

This is an activity that offers a flexible approach. The Challenge of the Day materials will be place on a dressed up cart (cart with a nice skirt). Two helium balloons will be fixed on the cart, on the first one will be written Challenge of the Day, on the second will be written Défi du jour. A poster located in plexiglass holder will be placed on the cart. The educator will go around the museum and offer visitors to participate. This way, visitors will not see the solutions that other visitors came up with.

The activity is roaming for 30 minutes to an hour, twice a day on the designated days.

Introduction 1 minute Bernouilli bag 5 minutes Egg in a bottle 5 minutes Cherry in the cup 5 minutes Conclusion 1 minute

Target Audiences: . Families with young or schools aged children . Students from 4 to 15 years old . Adults

Challenge of the Day, March Break 2012, last updated on March 1, 2012 Page 2 of 7 What you say Background Introduction

Hi! Welcome to Challenge of the day.

I have a challenge for you. There are rules to my challenge, you’ll have to listen carefully and tell how or show me how you will go about to solve it.

Challenge #1: Blowing a full bag Bernoulli's principle: I need at least two volunteers. I have these big bag (show the Bernouilli bags, hand one to each participant). My challenge is: Can you blow up completely using only one blow? Bernoulli’s principle helps explain that an aircraft can achieve lift because of the shape of its wings. They are Q. Do you think it is possible? Are you ready to try? Are you clear on the rules? Ready to start the challenge? Ready, set, GO! shaped so that that air flows faster over the top of the wing and slower underneath. Fast moving air equals low If a participant does it, ask how he did it, if you participant succeed, demonstrate how. air pressure while slow moving air equals high air pressure. The high air pressure underneath the wings To fill this bag with air with only one blow, you cannot fill it you fill a balloon, it would take more than one deep breath to do will therefore push the aircraft up through the lower air that. Instead I used Bernouilli principle. Bernouilli was an 18th century scientist who studied the dynamic between speed and pressure. pressure. Now this may sound odd, but he actually understood how airplane could fly before airplanes were invented! Other experience with the Bernouilli principle to suggest By blowing the air in front of the bag, but not directly into it, I created a stream of low pressure air which brought behind it to participants: enough of the surrounding air to fill the bag in only one blow. Bernouilli observed a relationship between air and its pressure. Bernouilli said that the faster the air moves the lower pressure it has. So I blew a very gentle and slow stream of low pressure air. Using a hairdryer, or blowing in a straw, to float ping-pong or polystyrene balls in the air. (straw and hairdryer must be I knew that the surrounding air had more pressure than my stream and that this higher pressure air would force its way into my underneath the ball) low pressure stream, because high pressures zones will always try to lessen its pressure. No one likes pressure, not even air. And that’s how I did it.

Q. Do you want to try using the Bernouilli principle this time?

Challenge #2: Egg in a bottle An air pressure difference causes movement of particles. The amount of pressure is determined by the difference My challenge today is: I have a hard boiled egg. I will place it at the top of this Erlenmeyer. Can you make it fall inside the of pressure in the air and the amount of area affected. container without touching it? This is also a good experiment to show that the use of Challenge of the Day, March Break 2012, last updated on March 1, 2012 Page 3 of 7 oxygen molecules in a particular area causes a loss of air Q. Do you think it is possible? pressure

I’ll help you out. You have to use a piece of paper and a match for this experiment. (egg in a bottle reference) Q. What should I do with the paper and the match?

A. I need to set fire to the paper and quickly put in the Erlenmeyer. Q. And then what? A. Place the egg on top of the opening. I need a volunteer for the next part. Ask the volunteer to hold the egg. I’ll set fire to the paper and place it inside the container. Once the piece of paper is inside, you need to do is place the egg at the opening very quickly. Are you ready? Put the egg when I tell you, not before, I don’t want you to burn yourself.

Q. What happened? A. The egg went in the bottle Q. Can someone tell me why the egg moved and got inside the bottle? A. Inside the Erlenmeyer, there was air, but then I added the paper on fire, and you blocked the opening with the egg, so no more air could go in. The fire burned using all the oxygen in the container. What this did is decreasing the pressure in the air and creating a vacuum. A vacuum is a space entirely devoid of matter, completely empty even or air.

The presence of this small vacuum lowered the air pressure in the container. So if the pressure inside the container became low, that means that the pressure outside the Erlenmeyer was higher right? So there was a difference of pressure inside and outside the Erlenmeyer when the egg was blocking the opening.

Q. Would you say that the egg what sucked in the Erlenmeyer, or was it pushed inside? A. It was pushed inside, what happen is the high pressure outside the jar pushed the egg to the opening of the jar, because high pressure always wants to reach the low pressure. So in summary, the high pressure outside the bottle pushed the egg inside the Erlenmeyer, it wasn’t sucked in.

Q. Now the question you all must have. How will I get the egg out? A. Easy, I need to do the opposite reaction. I will create a high pressure inside the jar so that the egg will be pushed out. To do that, I need to add some gas; that will increase the pressure. I have here vinegar and baking soda. I add baking soda in the Erlenmeyer, place the bowl on my cart to contain the mess if there is one, and quickly I will add vinegar inside and turn the Erlenmeyer upside down.

Q. Are you ready? Ask a volunteer to pour the vinegar. Ta Dah! (the egg should slip out). Challenge of the Day, March Break 2012, last updated on March 1, 2012 Page 4 of 7 Q. What happened exactly? A. The baking soda and the vinegar created a chemical reaction when placed together, and that reaction released carbon dioxide. The carbon dioxide is trapped inside the container which made a high pressure environment. As I said earlier, high pressure always tries to go to the lowest pressure. So the egg was pushed away from the high pressure into the low pressure environment, which this time was the outside of the Erlenmeyer.

Challenge #3: Floating cherry Note on the material: Empty the corn syrup in one when done and use a clean cup. Here we have an empty cup and we have a maraschino cherry. Let’s just say I want to create a nice table centerpiece for my party and I want to have a cherry float in the middle of my vase. Not at the top, not at the bottom, in the middle. One thing to How does it work? remember is I don’t care what liquid is in my vase; my goal is to make the cherry float, so the cup needs to be filled. The same amount of two different liquids will have different weights because they have different densities. The liquids that Q. How can I do that? weigh more (have a higher density) will sink below the liquids First, let’s put cherry in the cup. that weigh less (have a lower density). To test this, you might want to set up a scale and Material Density Q. What will happen if I add only water in my cup? Will the cherry move from the bottom of the glass? Let’s see. Ask a measure each of the liquids Vegetable Oil .92 participant to add a third of water in the cup. that you poured into your Water 1.00 A. The cherry sit still at the bottom and won’t budge. column. Make sure that you measure the weights Dawn Dish Soap 1.06 Q. How can I bring it up? of equal portions of each Light Corn Syrup 1.33 A. By adding a liquid which is denser than water. You see, all liquids are not the same. Just by looking at them, we can see liquid. You should find that difference between liquids some are coloured, some are transparent, other opaque, some are runny, other are thick. But for this the weights of the liquids correspond to each different layer experiment, we need to focus on one attribute: density. The density measures the mass of the liquid present within a specific of liquid. For example, the honey will weigh more than the space, this space is also called volume. The mass is measured in grams and the volume is measured in millilitres, so density Karo syrup. By weighing these liquids, you will find that measures how many grams of particles there are per mL of volume; the density is measured in g/mL (grams per millilitres). density and weight are closely related.

The table shows the densities of the liquids used in the Water has a 1 g/mL density. We tend to see water like a baseline. So a liquid which has more than 1 g of particles of liquid per ml column as well as other common liquids (measured in has a higher density than water, while a liquid with less than 1 g per ml has a lower density than water. For example, let’s take g/cm3 or g/mL). ketchup: it is made of vinegar and tomato paste. Density is basically how much "stuff" is smashed into a Q. Do you think ketchup is denser, less dense or as dense than water? Do you think there is more than 1 g of ketchup particles particular area... or a comparison between an object's mass per ml? and volume. Remember the all-important equation: Density = A. It is denser than water. One way to find out quickly would be to weigh the same volume of both water and ketchup. So If I put Mass divided by Volume. Based on this equation, if the weight 100 ml of water in a cup, and 100 ml of ketchup in another and weight them I would find that the water weight 100g, while the (or mass) of something increases but the volume stays the ketchup weight 140 g. same, the density has to go up. Likewise, if the mass Challenge of the Day, March Break 2012, last updated on March 1, 2012 Page 5 of 7 decreases but the volume stays the same, the density has to Q. What is the density of ketchup? go down. Lighter liquids (like water or rubbing alcohol) are A. We have to divide the mass by the volume; 140 g / 100 ml is 1.4 g/ml. less dense than heavy liquids (like honey or Karo syrup) and so float on top of the more dense layers. Q. So let’s see if we all understand what density is, what is the density of 100g of substance with a volume of 100 ml? (Steve Spangler, 7 layers experiment) A. 1 g/ml.

The difference of density of liquid means that the less dense liquids will float above the denser liquid. For example, whip cream on a hot chocolate, the cream floats on top right? Because the cream is less dense than the hot chocolate.

Q. So how can we apply this to our challenge? A. We need to find a liquid which is denser than the cherry and the water. I have a two liquid to try here: corn syrup and oil.

Q. Which one should we start with? If participants say oil, only pour a bit. Depending on the age of participant, you can ask for a volunteer. Pour in the liquid, add a cherry Q. Are the cherry moving up? A. No.

If the participants say corn syrup, pour a good amount, and then drop the cherry in. Depending on the age of participant, you can ask for a volunteer Q. Is the cherry at the bottom of the cup or at the top? A. At the top, so let’s put some more syrup until we get to the middle of the cup.

Q. So we can see that the cherry floats on top of the corn syrup, so what does that tells us about the density of the cherry? Is the cherry density higher or lower than the corn syrup? A. It is lower, because the cherries don’t sink in the layer of corn syrup.

Q. But earlier when we added water, the cherry would sink to the bottom, so is the cherry more of less dense than water? A. Is it denser than water, because it sank.

Q. Now that the cherry is where I want, what should liquid should I add to the cup to make sure the cup is filled and the cherry remains in the middle of the glass? A. We could add some oil; oil is less dense than water. The oil will float on top on the water, creating a new layer. We’ll be sure the cherry will stay in the middle layer since the cherry is also less dense than oil. But we could also fill it with water since the Challenge of the Day, March Break 2012, last updated on March 1, 2012 Page 6 of 7 cherry is denser than the water, it will remain at the bottom of the water layer. As long as we don’t add anything denser than water, the layer containing the cherry will remain at the same place.

Thanks for participating. CONCLUSION—1 minute

As you can see, to solve the challenge, we needed to use our observation skill. A big part of science is being able to observe.

Vocabulary translation: Challenge: défi Stream: courant Vacuum: vide Density: Densité

Materials:

 Bernouilli bags (6)  Plastic Cups (6)  Cherry in a jar  Bottle of water (tap water in fine)  Oil  Hard boiled eggs  Erlenmeyer (2)  Pieces of paper  Lighter  Corn syrup  Vinegar  Baking powder  Spoon

References:

Egg in a bottle: http://camillasenior.homestead.com/files/egg_in_a_bottle.pdf Seven Layer experiment: http://www.stevespanglerscience.com/experiment/seven-layer-density-column 9 layers experiment: http://www.youtube.com/watch?v=-CDkJuo_LYs

Challenge of the Day, March Break 2012, last updated on March 1, 2012 Page 7 of 7