This is the simplest form of camera – no film, no batteries, and no moving parts that can break. The biggest problem with this camera is that the inlet hole is so tiny that it lets in such a small amount of light and makes a faint image. If you make the hole larger, you get a brighter image, but it’s much less focused. The more light rays coming through, the more they spread out the image out more and create a fuzzier picture. You’ll need to play with the size of the hole to get the best image.

While you can go crazy and take actual photos with this camera by sticking on a piece of undeveloped black and white film (use a moderately fast ASA rating), I recommend using tracing paper and a set of eyeballs to view your images. Here’s what you need to do:

Materials:

• box
• tracing paper
• razor or scissors
• tape
• tack

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Download Student Worksheet & Exercises

Here’s the quick set of instructions:

1. Use a cardboard box that is light-proof (no leaks of light anywhere).
2. Seal light leaks with tape if you have to. Cut off one side of the box (Note – there’s no need to do this if you’re using a shoebox).
3. Tape a piece of tracing paper over the cutout side, keeping it taut and smooth.
4. Make a pinhole in the box side opposite of the tracing paper.
5. Point the pinhole at a window and move toward or away from the window until you see its image in clear focus on the tracing paper.

OPTIONAL: You can hold up a magnifying glass in front of the pinhole to sharpen the image.

Exercises

1.  How do the images appear when they’re projected onto the paper inside your camera?
2. Why do you think it’s important to make the box as light-proof as possible?
3. Is there a part of your body that works similarly to the pinhole?
4.  Sketch a picture of something you saw through your pinhole camera.

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In this lab, we are going to make an eyeball model using a balloon. This experiment should give you a better idea of how your eyes work. The way your brain actually sees things is still a mystery, but using the balloon we can get a good working model of how light gets to your brain.

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Here’s what you need

• • 1 biconvex plastic lens
  • 1 round balloon, white, 9 inches
  • 1 assistant
  • 1 votive candle
  • 1 black marker
  • 1 book of matches
  • 1 metric ruler
  • Adult Supervision!

Download Student Worksheet & Exercises

Here’s what you do

1. Blow up the balloon until it is about the size of a grapefruit. If it’s difficult to inflate, stretch the material a few times or ask an adult to help you.
2. You will need an extra set of hands for this portion. Ask your partner to hold the neck of the balloon closed to keep the air in while you insert the lens into the opening. The lens will need to be inserted perpendicularly to the balloon’s neck. It will prevent any air from escaping once it’s in place. Like your eye, light will enter through the lens and travel toward the back of the balloon.
3. Hold the balloon so that the lens is pointing toward you. Take the lens between your thumb and index finger. Look into the lens into the balloon. You should have a clear view of the inside. Start to twist the balloon a little and notice that the neck gets smaller like your pupils do when exposed to light. Practice opening and closing the balloon’s “pupil.”
4. Have an adult help you put the candle on the table and light it. Turn out the lights.
5. Put the balloon about 20 to 30 centimeters away from the candle with the lens pointed toward it. The balloon should be between you and the candle. You should see a projection of the candle’s flame on the back of the balloon’s surface. Move the balloon back and forth in order to better focus the image on the back of the balloon and then proceed with data collection.
6.  Describe the image you see on the back of the balloon. How is it different from the flame you see with your eyes? Draw a picture of how the flame looks.
7. The focal length is the distance from the flame to the image on the balloon. Measure this distance and record it.
8. What happens if you lightly push down on the top of the balloon? Does this affect the image? You are experimenting with the affect caused by near-sightedness.
9. To approximate a farsighted eye, gently push in the front and back of the balloon to make it taller. How does this change what you see?

What’s going on?

Okay, let’s discuss the part of the balloon that relate to parts of your eye. The white portion of the balloon represents your sclera, which you may have already guessed is also the white part of your eye. It is actually a coating made of protein that covers the various muscle in your eye and holds everything together.

Of course, the lens you inserted represents the actual lens in your eye. The muscles surrounding the lens are called ciliary muscles and they are represented by the rubber neck of your balloon. The ciliary muscles help to control the amount of light entering your eyes.

The retina is in the back of your eye, which is represented by the inside back of your balloon. The retina supports your rods and cones. They collect information about light and color and send it to your brain.

Exercises

1.      How does your eye work like a camera?
2.      How can you tell if a lens is double convex?
3.      What is the difference between convex and concave?
4.      Can you give an example of an everyday object that has both a convex and a concave side?
5.      How can you change the balloon to make it like a near-sighted eye?
6.      How can you change the balloon to make it like a far-sighted eye?

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Are you curious about pulleys? This set of experiments will give you a good taste of what pulleys are, how to thread them up, and how you can use them to lift heavy things.

We’ll also learn how to take data with our setup and set the stage for doing the ultra-cool Pulley Lift experiments.

Are you ready?
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For this experiment, you will need:

• One pulley (from the hardware store… get small ones that spin as freely as possible. You’ll need three single pulleys or if you can find one get a double pulley to make our later experiment easier.)
• About four feet of string
• 2 paper cups
• many little masses (about 50 marbles, pennies, washers etc.)
• Yardstick or measuring tape
• A scale (optional)
• 2 paper clips
• Nail or some sort of sharp pokey thing
• Table

 
Download Student Worksheet & Exercises

“Advanced students: Download your Simple Pulley Experiments

1. Take a look at the video to see how to make your “mass carriers”. Use the nail to poke a hole in both sides of the cup. Be careful to poke the cup…not your finger! Thread about 4 inches of string or a pipe cleaner through both holes. Make sure the string is a little loose. Make two of these mass carriers. One is going to be your load (what you lift) and the other is going to be your effort (the force that does the lifting).

2. Dangle the pulley from the table (check out the picture).

3. Bend your two paper clips into hooks.

4. Take about three feet of string and tie your paper clip hooks to both ends.

5. Thread your string through the pulley and let the ends dangle.

6. Put 40 masses (coins or whatever you’re using) into one of the mass carriers. Attach it to one of the strings and put it on the floor. This is your load.

7. Attach the other mass carrier to the other end of the string (which should be dangling a foot or less from the pulley). This is your effort.

8. Drop masses into the effort cup. Continue dropping until the effort can lift the load.

9. Once your effort lifts the load, you can collect some data. First allow the effort to lift the load about one foot (30 cm) into the air. This is best done if you manually pull the effort until the load is one foot off the ground. Measure how far the effort has to move to lift the load one foot.

10. When you have that measurement, you can either count the number of masses in the load and the effort cup or if you have a scale, you can get the mass of the load and the effort.

11. Write your data into your pulley data table in your science journal.

Double Pulley Experiment

You need:

Same stuff you needed in Experiment 1, except that now you need two pulleys.

1. Attach the string to the hook that’s on the bottom of your top pulley.

2. Thread the string through the bottom pulley.

3. Thread the string up and through the top pulley.

4. Attach the string to the effort.

5. Attach the load to the bottom pulley.

6. Once you get it all together, do the same thing as before. Put 40 masses in the load and put masses in the effort until it can lift the load.

7. When you get the load to lift, collect the data. How far does the effort have to move now in order to lift the load one foot (30 cm)? How many masses (or how much mass, if you have a scale) did it take to lift the load?

8. Enter your data into your pulley table in your science journal.

Triple Pulley Experiment

You Need

Same stuff as before

If you have a double pulley or three pulleys you can give this a shot. If not, don’t worry about this experiment.

Do the same thing you did in experiments 1 and 2 but just use 3 pulleys. It’s pretty tricky to rig up 3 pulleys so look carefully at the pictures. The top pulley in the picture is a double pulley.

1. Attach the string to the bottom pulley. The bottom pulley is the single pulley.

2. Thread the string up and through one of the pulleys in the top pulley. The top pulley is the double pulley.

3. Take the string and thread it through the bottom pulley.

4. Now keep going around and thread it again through the other pulley in the top (double) pulley.

5. Almost there. Attach the load to the bottom pulley.

6. Last, attach the effort to the string.

7. Phew, that’s it. Now play with it!

Take a look at the table and compare your data. If you have decent pulleys, you should get some nice results. For one pulley, you should have found that the amount of mass it takes to lift the load is about the same as the amount of mass of the load. Also, the distance the load moves is about the same as the distance the effort moves.

All you’re really doing with one pulley, is changing the direction of the force. The effort force is down but the load moves up.

Now, however, take a look at two pulleys. The mass needed to lift the load is now about half the force of the load itself! The distance changed too. Now the distance you needed to move the effort, is about twice the distance that the load moves. When you do a little math, you notice that, as always, work in equals work out (it won’t be exactly but it should be pretty close if your pulleys have low friction).

What happened with three pulleys? You needed about 1/3 the mass and 3 times the distance right? With a long enough rope, and enough pulleys you can lift anything! Just like with the lever, the pulley, like all simple machines, does a force and distance switcheroo.

The more distance the string has to move through the pulleys, the less force is needed to lift the object. The work in, is equal to the work out (allowing for loss of work due to friction) but the force needed is much less.

Exercises Answer the questions below:

1. What is the load and effort of a pulley? Draw a pulley and label it.
2. What is the best way to say what a simple machine helps us do?
   1. Do work without changing force applied
   2. Change the direction or strength of a force
   3. Lift heavy shipping containers
   4. None of these
3.  Name one other type simple machine and an example:

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We’re going to use everyday objects to build a simple machine and learn how to take data. Sadly, most college students have trouble with these simple steps, so we’re getting you a head start here. The most complex science experiments all have these same steps that we’re about to do… just on a grander (and more expensive) scale. We’re going to break each piece down so you can really wrap your head around each step. Are you ready to put your new ideas to the test?

This experiment is for Advanced Students.

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You need:

• A wooden ruler or a paint stick for the lever
• Many pennies, quarters, or washers (many little somethings of the same mass)
• A spool, eraser, pencil (anything that can be your fulcrum)
• A ruler (to be your um….ruler)
• Paper cups
• Optional: A scale that can measure small amounts of mass (a kitchen scale is good)

Download Student Worksheet & Exercises

1. Tape one paper cup to each end of lever. (This allows for an easy way to hold the pennies on the lever.)

2. Set your fulcrum on the table and put your lever (ruler or paint stick) on top of it. Try to get the ruler to balance on the fulcrum.

3. Put five pennies on one side of your lever.

4. Now, put pennies, one at a time on the other side of your lever, this is your effort. Keep adding pennies until you get your lever to come close to balancing. Try to keep your fulcrum in the same place on your lever. You may even want to tape it there.

5. Count the pennies on the effort side and count the pennies on the load side. If you have a scale, you can weigh them as well. With the fulcrum in the middle you should see that the pennies/mass on both sides of the lever are close to equal.

6. This part’s a little tricky. Measure how high the lever was moved. On the load side, measure how far the lever moved up and on the effort side measure how far the lever moved down. Be sure to do the measuring at the very ends of the lever.

7. Write your results in your science journal as shown in the video.

8. Remove the pennies and do it all over again, this time move the fulcrum one inch (two centimeters) closer to the load side.

9. Continue moving the fulcrum closer to the load until it gets too tough to do. You’ll probably be able to get it an inch or two (two to four centimeters) from the load.

10. If you didn’t use a scale feel free to stop here. Don’t worry about the “work in” and “work out” parts of the table. Take a look at your table and check out your results. Can you draw any conclusions about the distance the load moved, the distance the effort moved, and the amount of force required to move it?

11. If you used a scale to get the masses you can find out how much work you did. Remember that work=force x distance. The table will tell you how to find work for the effort side (work in) and for the load side (work out). You can multiply what you have or if you’d like to convert to Joules, which is a unit of work, feel free to convert your distance measurements to meters and your mass measurements to Newtons. Then you can multiply meters times Newtons and get Joules which is a unit of work.

1 inch = .025 meters

1 cm = .01 meter

1 ounce =0.278 Newtons

1 gram = 0.0098 Newtons

By taking a look at your data and by all the other work we did this lesson, you can see the beautiful switcheroo of simple machines. Simple machines sacrifice distance for force. With the lever, the farther you had to push the lever, the less force had to be used to move the load.

The work done by the effort is the same as the work done on the load. By doing a little force/distance switcheroo, moving the load requires much less force to do the work. In other words, it’s much easier. Anything that makes work easier gets a thumbs up by me! Hooray for simple machines!

Exercises

1. What is work?
   1. Force against an object
   2. Force over distance
   3. 9 hours and sweat
   4. Energy applied to an object
2. What is the unit we use to measure energy?
   1. Newton
   2. Watt
   3. Joule
   4. Horsepower
3. Describe a first class lever using one example.

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Levers are classified into three types: first class, second class, or third class. Their class is identified by the location of the load, the force moving the load, and the fulcrum. In this activity, you will learn about the types of levers and then use your body to make each type.

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Here’s what you need

• • 1 body

Download Student Worksheet & Exercises

Here’s what you do

1. In a first class lever, the fulcrum is in the middle. The load and effort are on opposite sides with the fulcrum between them. A familiar example of a first class lever is a see saw.
2. A second class lever has the fulcrum on one end, the load in the middle, and the force on the end opposite the fulcrum. A wheelbarrow is a good example of a second class lever.
3. Lastly, a third class lever has a fulcrum on one end and the load on the opposite end. The force is applied in the middle in this type of lever. A golf club is an example of a third class lever.
4. Use the photos to identify the levers of each type in your body.

What’s going on?

Only read further if you have had an opportunity to identify the levers in the pictures. Spoilers below!

Your head moving up and down on your spine is an example of a first class lever. Your neck joint in the middle is the fulcrum, with load and effort on either side. In this example, load and effort switch depending on whether you are moving your head up or down.

Standing on tiptoe is an example of a second class lever where your toes are the fulcrum. The effort, or force, is in your heels – they are lifting your body up. And the resistance is located between your toes and heels.

This leaves us with bicep curls, which are an example of a third class lever. Your elbow serves as the fulcrum, the bicep is the force, and the weight in your hand on the end is the load.

Just for fun, did you know your knee is the largest joint in your whole body? It connects your femur, the largest bone, to the bones of your lower leg. Your smallest joints are the anvil, hammer, and stirrup in your inner ear.

Exercises

1. Draw a diagram of a first-class lever. Where in your body is this type of lever?
2. Draw a diagram of a third-class lever. Where will you find this?
3. Draw a diagram of a second-class lever. Can you give an example of this type of lever in the real world?

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When you drop a ball, it falls 16 feet the first second you release it. If you throw the ball horizontally, it will also fall 16 feet in the first second, even though it is moving horizontally… it moves both away from you and down toward the ground. Think about a bullet shot horizontally. It travels a lot faster than you can throw (about 2,000 feet each second). But it will still fall 16 feet during that first second. Gravity pulls on all objects (like the ball and the bullet) the same way, no matter how fast they go.

What if you shoot the bullet faster and faster? Gravity will still pull it down 16 feet during the first second, but remember that the surface of the Earth is round. Can you imagine how fast we’d need to shoot the bullet so that when the bullet falls 16 feet in one second, the Earth curves away from the bullet at the same rate of 16 feet each second?

Answer: that bullet needs to travel nearly 5 miles per second. (This is also how satellites stay in orbit – going just fast enough to keep from falling inward and not too fast that they fly out of orbit.)

Catapults are a nifty way to fire things both vertically and horizontally, so you can get a better feel for how objects fly through the air. Notice when you launch how the balls always fall at the same rate – about 16 feet in the first second.  What about the energy involved?

When you fire a ball through the air, it moves both vertically and horizontally (up and out). When you toss it upwards, you store the (moving) kinetic energy as potential energy, which transfers back to kinetic when it comes whizzing back down. If you throw it only outwards, the energy is completely lost due to friction.

The higher you pitch a ball upwards, the more energy you store in it. Instead of breaking our arms trying to toss balls into the air, let’s make a simple machine that will do it for us. This catapult uses elastic kinetic energy stored in the rubber band to launch the ball skyward.

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Here’s what you need:

• 9 tongue-depressor size popsicle sticks
• four rubber bands
• one plastic spoon
• ping pong ball or wadded up ball of aluminum foil (or something lightweight to toss, like a marshmallow)
• hot glue gun with glue sticks

 
Download Student Worksheet & Exercises

What’s going on? We’re utilizing the “springy-ness” in the popsicle stick to fling the ball around the room. By moving the fulcrum as far from the ball launch pad as possible (on the catapult), you get a greater distance to press down and release the projectile. (The fulcrum is the spot where a lever moves one way or the other – for example, the horizontal bar on which a seesaw “sees” and “saws”.)

Troubleshooting: These simple catapults are quick and easy versions of the real thing, using a fulcrum instead of a spring so kids don’t knock their teeth out. After making the first model, encourage kids to make their own “improvements” by handing them additional popsicle sticks, spoons, and glue sticks (for the hot glue guns).

If they get stuck, you can show them how to vary their models: glue a second (or third, fourth, or fifth) spoon onto the first spoon for multi-ammunition throws, increase the number of popsicle sticks in the fulcrum from 7 to 13 (or more?), and/or use additional sticks to lengthen the lever arm. Use ping pong balls as ammo and build a fort from sheets, pillows, and the backside of the couch.

Want to make a more advanced catapult? 

This catapult requires a little more time, materials, and effort than the catapult design above, but it’s totally worth it. This device is what most folks think of when you say ‘catapult’. I’ve shown you how to make a small model – how large can you make yours?

This project lends itself well to taking data and graphing your results: you and your child can jot down the distance traveled along with time aloft with further calculations for high school students for velocity and acceleration. My university students would also calculate statistics, percent error, and more. My students also mapped out the material properties of the ‘cantilevered beam’ as well as model the popsicle stick as a spring (to determine the spring constant (k) for your calculations from Hooke’s Law). You can take this project as far as you want, depending on the interest and ability of kids.

Materials:

• plastic spoon
• 14 popsicle sticks
• 3 rubber bands
• wooden clothespin
• straw
• wood skewer or dowel
• scissors
• hot glue gun

Try different ball weights (ping pong, foil crumpled into a ball, whiffle balls, marshmallows, etc) and chart out the results: make a data table that shows what ball you tried and how far it went. You can also use a stopwatch to time how long your ball was in the air.

You can also graph your results: make a chart where you plot each data point on a graph that has distance on the vertical axis and time on the horizontal axis.

Advanced Teaching Tips: For high school and college-level physics classes, you can easily incorporate these launchers into your calculations for projectile motion. Offer students different ball weights (ping pong, foil crumpled into a ball, and whiffle balls work well) and chart out the results.

Exercises Answer the questions below:

1. How is gravity related to kinetic energy?
   1. Gravity creates kinetic energy in all systems.
   2. Gravity explains how potential energy is created.
   3. Gravity pulls an object and helps its potential energy convert into kinetic energy.
   4. None of the above
2. If you could use your catapult to launch your ball of foil into orbit, how high would it have to go?
   1. Above the atmosphere
   2. High enough to slingshot around the moon
   3. High enough so that when it falls, the earth curves away from it
   4. High enough so that it is suspended in empty space
3. Where is potential energy the greatest on the catapult?

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This is a very simple yet powerful demonstration that shows how potential energy and kinetic energy transfer from one to the other and back again, over and over.  Once you wrap your head around this concept, you’ll be well on your way to designing world-class roller coasters.

For these experiments, find your materials:

• some string
• a bit of tape
• a washer or a weight of some kind
• set of magnets (at least 6, but more is better)

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Here’s what you do:

1. Make the string into a 2 foot or so length.

2. Tie the string to the washer, or weight.

3. Tape the other end of the string to a table.

4. Lift the weight and let go, causing the weight to swing back and forth at the end of the pendulum.

Download Student Worksheet & Exercises

Watch the pendulum for a bit and describe what it’s doing as far as energy goes. Some questions to think about include:

• Where is the potential energy greatest?
• Where is the kinetic energy greatest?
• Where is potential energy lowest?
• Where is kinetic energy lowest?
• Where is KE increasing, and PE is decreasing?
• Where is PE increasing and KE decreasing?
• Where did the energy come from in the first place?

Remember, potential energy is highest where the weight is the highest.

Kinetic energy is highest were the weight is moving the fastest. So potential energy is highest at the ends of the swings. Here’s a coincidence, that’s also where kinetic energy is the lowest since the weight is moving the least.

Where’s potential energy the lowest? At the middle or lowest part of the swing. Another coincidence, this is where kinetic energy is the highest! Now, wait a minute…coincidence or physics? It’s physics right?

In fact, it’s conservation of energy. No energy is created or destroyed, so as PE gets lower KE must get higher. As KE gets higher PE must get lower. It’s the law…the law of conservation of energy! Lastly, where did the energy come from in the first place? It came from you. You added energy (increased PE) when you lifted the weight.

(By the way, you did work on the weight by lifting it the distance you lifted it. You put a certain amount of Joules of energy into the pendulum system. Where did you get that energy? From your morning Wheaties!)

Chaos Pendulum

For this next experiment, we’ll be using magnets to add energy into the system by having a magnetic pendulum interact with magnets carefully spaced around the pendulum. Watch the video to learn how to set this one up.  You’ll need a set of magnets (at least one of them is a ring magnet so you can easily thread a string through it), tape, string, and a table or chair. Are you ready?

Exercises

1. Why can we never make a machine that powers itself over and over again?
   1. Energy is mostly lost to heat.
   2. Energy is completely used up.
   3. Energy is unlimited, but is absorbed by neighboring air molecules.
   4. None of these
2. In the pendulum, as kinetic energy increases, potential energy ______________.
   1. Increases
   2. Decreases
3. As potential energy decreases, kinetic energy _________________.
   1. Increases
   2. Decreases

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Note: Do the pendulum experiment first, and when you’re done with the heavy nut from that activity, just use it in this experiment.

You can easily create one of these mystery toys out of an old baking powder can, a heavy rock, two paper clips, and a rubber band (at least 3″ x 1/4″).  It will keep small kids and cats busy for hours.

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Here’s what you get:

• can with a lid
• heavy rock or large nut
• two paper clips
• rubber band

You’ll need two holds punched through your container  – one in the lid and the bottom. Thread your rubber band through the heavy washer and tie it off (this is important!).  Poke the ends of the rubber band through one of the holes and catch it on the other side with a paper clip.  (Just push a paper clip partway through so the rubber band doesn’t slip back through the hole.)  Do this for both sides, and make sure that your rubber band is a pulled mildly-tight inside the can.  You want the hexnut to dangle in the center of the can without touching the sides of the container.

 
Download Student Worksheet & Exercises

Now for the fun part… gently roll the can on a smooth floor away from you.  The can should roll, slow down, stop, and return to  you!  If it doesn’t, check the rubber band tightness inside the can.

The hexnut is a weight that twists up the rubber band as the can rolls around it.  The kinetic energy (the rolling motion of the can) transforms into potential (elastic) energy stored in the rubber band the free side twists around. The can stops (this is the point of highest potential energy) and returns to you (potential energy is being transformed into kinetic). The farther the toy is rolled the more elastic potential energy it stores.

Exercises

1. Explain in your own words two types of energy transfer:
2. True or false: All energy in a system is lost to heat.
   1. True
   2. False

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This is a nit-picky experiment that focuses on the energy transfer of rolling cars.  You’ll be placing objects and moving them about to gather information about the potential and kinetic energy.

We’ll also be taking data and recording the results as well as doing a few math calculations, so if math isn’t your thing, feel free to skip it.

Here’s what you need:

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• a few toy cars (or anything that rolls like a skate)
• a board, book or car track
• measuring tape

The setup is simple.  Here’s what you do:

1. Set up the track (board or book so that there’s a nice slant to the floor).

2. Put a car on the track.

3. Let the car go.

4. Mark or measure how far it went.

Download Student Worksheet & Exercises

As you lifted the car onto the track you gave the car potential energy. As the car went down the track and reached the floor the car lost potential energy and gained kinetic energy. When the car hit the floor it no longer had any potential energy only kinetic.

If the car was 100% energy efficient, the car would keep going forever. It would never have any energy transferred to useless energy. Your cars didn’t go forever did they? Nope, they stopped and some stopped before others. The ones that went farther were more energy efficient. Less of their energy was transferred to useless energy than the cars that went less far.

Where did the energy go? To heat energy, created by the friction of the wheels, and to sound energy. Was energy lost? NOOOO, it was only changed. If you could capture the heat energy and the sound energy and add it to the the kinetic energy, the sum would be equal to the original amount of energy the car had when it was sitting on top of the ramp.

For K-8 grades, click here to download a data sheet.

For Advanced Students, click  here for the data log sheet. You’ll need Microsoft Excel to use this file.

Exercises

1. Where is the potential energy greatest?
2. Where is the kinetic energy greatest?
3. Where is potential energy lowest?
4. Where is kinetic energy lowest?
5. Where is KE increasing, and PE is decreasing?
6. Where is PE increasing and KE decreasing?

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Bobsleds use the low-friction surface of ice to coast downhill at ridiculous speeds. You start at the top of a high hill (with loads of potential energy) then slide down a icy hill til you transform all that potential energy into kinetic energy.  It’s one of the most efficient ways of energy transformation on planet Earth. Ready to give it a try?

This is one of those quick-yet-highly-satisfying activities which utilizes ordinary materials and turns it into something highly unusual… for example, taking aluminum foil and marbles and making it into a racecar.

While you can make a tube out of gift wrap tubes, it’s much more fun to use clear plastic tubes (such as the ones that protect the long overhead fluorescent lights). Find the longest ones you can at your local hardware store. In a pinch, you can slit the gift wrap tubes in half lengthwise and tape either the lengths together for a longer run or side-by-side for multiple tracks for races. (Poke a skewer through the rolls horizontally to make a quick-release gate.)

Here’s what you need:

• aluminum foil
• marbles (at least four the same size)
• long tube (gift wrapping tube or the clear protective tube that covers fluorescent lighting is great)

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If you’re finding that the marbles fall out before the bobsled reaches the bottom of the slide, you need to either crimp the foil more closely around the marbles or decrease your hill height.

Check to be sure the marbles are free to turn in their “slots” before launching into the tube – if you’ve crimped them in too tightly, they won’t move at all. If you oil the bearings with a little olive oil or machine oil, your tube will also get covered with oil and later become sticky and grimy… but they sure go faster those first few times!

 
Download Student Worksheet & Exercises

Exercises Answer the questions below:

1. Potential energy is energy that is related to:
   1. Equilibrium
   2. Kinetic energy
   3. Its system
   4. Its elevation
2. If an object’s energy is mostly being used to keep that object in motion, we can say it has what type of energy?
   1. Kinetic energy
   2. Potential energy
   3. Heat energy
   4. Radiation energy
3. True or False: Energy is able to remain in one form that is usable over and over again.
   1. True
   2. False

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We’re going to build monster roller coasters in your house using just a couple of simple materials. You might have heard how energy cannot be created or destroyed, but it can be transferred or transformed (if you haven’t that’s okay – you’ll pick it up while doing this activity).

Roller coasters are a prime example of energy transfer: You start at the top of a big hill at low speeds (high gravitational potential energy), then race down a slope at break-neck speed (potential transforming into kinetic) until you bottom out and enter a loop (highest kinetic energy, lowest potential energy). At the top of the loop, your speed slows (increasing your potential energy), but then you speed up again and you zoom near the bottom exit of the loop (increasing your kinetic energy), and you’re off again!

Here’s what you need:

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• marbles
• masking tape
• 3/4″ pipe foam insulation (NOT neoprene and NOT the kind with built-in adhesive tape)

To make the roller coasters, you’ll need foam pipe insulation, which is sold by the six-foot increments at the hardware store. You’ll be slicing them in half lengthwise, so each piece makes twelve feet of track. It comes in all sizes, so bring your marbles when you select the size. The ¾” size fits most marbles, but if you’re using ball bearings or shooter marbles, try those out at the store. (At the very least you’ll get smiles and interest from the hardware store sales people.) Cut most of the track lengthwise (the hard way) with scissors. You’ll find it is already sliced on one side, so this makes your task easier. Leave a few pieces uncut to become “tunnels” for later roller coasters.

Read for some ‘vintage Aurora’ video? This is one of the very first videos ever made by Supercharged Science:

Download Student Worksheet & Exercises

Tips & Tricks

Loops Swing the track around in a complete circle and attach the outside of the track to chairs, table legs, and hard floors with tape to secure in place. Loops take a bit of speed to make it through, so have your partner hold it while you test it out before taping. Start with smaller loops and increase in size to match your entrance velocity into the loop. Loops can be used to slow a marble down if speed is a problem.

Camel-Backs Make a hill out of track in an upside-down U-shape. Good for show, especially if you get the hill height just right so the marble comes off the track slightly, then back on without missing a beat.

Whirly-Birds Take a loop and make it horizontal. Great around poles and posts, but just keep the bank angle steep enough and the marble speed fast enough so it doesn’t fly off track.

Corkscrew Start with a basic loop, then spread apart the entrance and exit points. The further apart they get, the more fun it becomes. Corkscrews usually require more speed than loops of the same size.

Jump Track A major show-off feature that requires very rigid entrance and exit points on the track. Use a lot of tape and incline the entrance (end of the track) slightly while declining the exit (beginning of new track piece).

Pretzel The cream of the crop in maneuvers. Make a very loose knot that resembles a pretzel. Bank angles and speed are the most critical, with rigid track positioning a close second. If you’re having trouble, make the pretzel smaller and try again. You can bank the track at any angle because the foam is so soft. Use lots of tape and a firm surface (bookcases, chairs, etc).

Troubleshooting Marbles will fly everywhere, so make sure you have a lot of extras! If your marble is not following your track, look very carefully for the point of departure – where it flies off.

-Does the track change position with the weight of the marble, making it fly off course? Make the track more rigid by taping it to a surface.
-Is the marble jumping over the track wall? Increase your bank angle (the amount of twist the track makes along its length).
-Does your marble just fall out of the loop? Increase your marble speed by starting at a higher position. When all else fails and your marble still won’t stay on the track, make it a tunnel section by taping another piece on top the main track. Spiral-wrap the tape along the length of both pieces to secure them together.

HOT TIPS for ULTRA-COOL PARENTS: This lab is an excellent opportunity for kids to practice their resilience, because we guarantee this experiment will not work the first several times they try it. While you can certainly help the kids out, it’s important that you help them figure it out on their own. You can do this by asking questions instead of rushing in to solve their problems. For instance, when the marble flies off the track, you can step back and say:

“Hmmm… did the marble go to fast or too slow?”

“Where did it fly off?”

“Wow – I’ll bet you didn’t expect that to happen. Now what are you going to try?”

Become their biggest fan by cheering them on, encouraging them to make mistakes, and try something new (even if they aren’t sure if it will work out).

Check out this cool roller coaster from one of our students!

Exercises 

1. What type of energy does a marble have while flying down the track of a roller coaster?
2. What type of energy does the marble have when you are holding it at the top of the track?
3. At the top of a camel back hill, which is higher for the marble, kinetic or potential energy?
4. At the top of an inverted loop, which energy is higher, kinetic or potential energy?

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This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too!

We’re going to cover energy and motion by building roller coasters and catapults! Kids build a working catapult while they learn about the physics of projectile motion and storing elastic potential energy. Let’s discover the mysterious forces at work behind the thrill ride of the world’s most monstrous roller coasters, as we twist, turn, loop and corkscrew our way through g-forces, velocity, acceleration, and believe it or not, move through orbital mechanics, like satellites. We’ll also learn how to throw objects across the room in the name of science… called projectile motion. Are you ready for a fast and furious physics class?

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Materials:

• • click for worksheet
  • marbles
  • masking tape
  • 3/4″ pipe foam insulation (NOT neoprene and NOT the kind with built-in adhesive tape)
  • 9 popsicle sticks
  • 4 rubber bands
  • one plastic spoon
  • ping pong ball
  • hot glue gun with glue sticks

Key Concepts

Centripetal means ‘center-seeking’. It’s the force that points toward the center of the circle you’re moving on. When you swing the bucket around your head, the bottom of the bucket is making the water turn in a circle and not fly away. Your arm is pulling on the handle of the bucket, keeping it turning in a circle and not fly away. That’s centripetal force. Centrifugal force is equal and opposite to centripetal force. Centrifugal means ‘center-fleeing’, so it’s a force that’s in the opposite direction. The car pushing on you is the centripetal force.The push of your weight on the door is the REACTIVE centrifugal force, meaning that it’s only there when something’s happening. It’s not a real force that goes around pushing and pulling on its own.

What’s Going On?

Engines used to use an automatic feedback system called a centrifugal governor to regulate the speed. For example, if you’re mowing the lawn and you hit a dry patch with no grass, the blades don’t suddenly spin wildly faster… they get adjusted automatically by a feedback system so maintains the same speed for the blades, so matter how thick or thin the grass that your cutting is. You’ll find these also in airplanes to automatically adjust the pitch (or angle) of the propeller as it moves through the air. The pilot sets the intended speed, and the airplane has a governor that helps adjust the angle the blades make with the air to maintain this speed automatically, because the air density changes with altitude. It’s really important to know how much centrifugal force people experience, whether its in cars or roller coasters! In fact roller coaster loops used to be circular, but now they use clothoid loops instead to keep passengers happy during their ride so they don’t need nearly the acceleration that they’d need for a circular loop (which means less g-force so passengers don’t black out).

Here are more roller coaster maneuvers you can try out:

Loops: Swing the track around in a complete circle and attach the outside of the track to chairs, table legs, and hard floors with tape to secure in place. Loops take a bit of speed to make it through, so have your partner hold it while you test it out before taping. Start with smaller loops and increase in size to match your entrance velocity into the loop. Loops can be used to slow a marble down if speed is a problem.

Camel-Backs: Make a hill out of track in an upside-down U-shape. Good for show, especially if you get the hill height just right so the marble comes off the track slightly, then back on without missing a beat.

Whirly-Birds: Take a loop and make it horizontal. Great around poles and posts, but just keep the bank angle steep enough and the marble speed fast enough so it doesn’t fly off track.

Corkscrew: Start with a basic loop, then spread apart the entrance and exit points. The further apart they get, the more fun it becomes. Corkscrews usually require more speed than loops of the same size.

Jump Track: A major show-off feature that requires very rigid entrance and exit points on the track. Use a lot of tape and incline the entrance (end of the track) slightly while declining the exit (beginning of new track piece).

Troubleshooting

Marbles will fly everywhere, so make sure you have a lot of extras! If your marble is not following your track, look very carefully for the point of departure – where it flies off. For instance, when the marble flies off the track, you can step back and say:

“Hmmm… did the marble go to fast or too slow?”

“Where did it fly off?”

“Wow – I’ll bet you didn’t expect that to happen. Now what are you going to try?”

Become their biggest fan by cheering them on, encouraging them to make mistakes, and try something new (even if they aren’t sure if it will work out).

Questions to Ask

1. Does the track change position with the weight of the marble, making it fly off course? (You can make the track more rigid by taping it to a surface.)
2. Is the marble jumping over the track wall? (You can increase your bank angle – the amount of twist the track makes along its length.)
3. How can you make your marble zip through two loops at once?
4. How could you increase your marble speed?
5. Where would you put a tunnel? (Leave one piece of track uncut to use as a tunnel.)

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