Driveway Races

Thursday September 10, 2009

soccerball1This experiment is one of my favorites in this acceleration series, because it clearly shows you what acceleration looks like.


The materials you need is are:


  • a hard, smooth ball (a golf ball, racket ball, pool ball, soccer ball, etc.)
  • tape or chalk
  • a slightly sloping driveway (you can also use a board for a ramp that’s propped up on one end)

For advanced students, you will also need: a timer or stopwatch, pencil, paper, measuring tape or yard stick, and this printout.


Grab a friend to help you out with this experiment – it’s a lot easier with two people.


Are you ready to get started really discovering what acceleration is all about?


Here’s what you do:
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Gyro Wheel

Thursday September 10, 2009

gyro1Gyroscopes defy human intuition, common sense, and even appear to defy gravity. You’ll find them in aircraft navigation instruments, games of Ultimate Frisbee, fast bicycles, street motorcycles, toy yo-yos, and the Hubble Space Telescope. And of course, the toy gyroscope (as shown here). Gyroscopes are used at the university level to demonstrate the principles of angular momentum, which is what we’re going to learn about here.


If you happen to have one of these toy gyroscopes, pull it out and play with it (although it’s not essential to this experiment). Notice that you can do all sorts of things with it when you spin it up, such as balance it on one finger (or even on a tight string). Wrap one end with string and hold the string vertically and you’ll find the gyro slowly rotates about the vertical string instead of flopping downward (as most objects do in Earth’s gravitational field). But why? Here’s the answer in plain English:


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Downhill Race

Thursday September 10, 2009

Newton’s Second Law is one of the toughest of the laws to understand but it is very powerful. In its mathematical form, it is so simple, it’s elegant. Mathematically it is F=ma or Force = Mass x Acceleration. An easy way to remember that is to think of your mother trying to get you out of bed in the morning. Force equals MA’s coming to get you! (I did mention how bad physics jokes are, right?)


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TaaDaaaaa!!!

Thursday September 10, 2009

Ever wonder how magicians work their magic? This experiment is worthy of the stage with a little bit of practice on your end.


Here’s how this activity is laid out: First, watch the video below. Next, try it on your own. Make sure to send us your photos of your inventions here!


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Rocket Car

Thursday September 10, 2009
busLet's take a good look at Newton's Laws in motion while making something that flies off in both directions. This experiment will pop a cork out of a bottle and make the cork fly go 20 to 30 feet, while the vehicle moves in the other direction!

This is an outdoor experiment. Be careful with this, as the cork comes out with a good amount of force. (Don’t point it at anyone or anything, even yourself!)

Here's what you need to find:

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Why bother with seat belts and helmets?

Thursday September 10, 2009
Every wonder why you have to wear a seat belt or wear a helmet? Let's find out (safely) by experimenting with a ball.

You will need to find:
  • a car
  • a licensed driver
  • a ball
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Newton’s Wagon

Thursday September 10, 2009

This is a quick and easy demonstration of how to teach Newton’s laws with minimal fuss and materials. All you need is a wagon, a rock, and some friends. We’re going to do a few totally different experiments using the same materials, though, so keep up with the changes as you read through the experiment.


Remember that Newton covers a few different ideas. First, there’s the idea that objects in motion will stay going they way they’re headed, unless something gets in the way. Then there’s the resistance to motion (objects at rest tend to stay put), as well as force being proportional to how fast you can get something to move (acceleration). And lastly, there’s the idea that forces happen in pairs – if you shoot something one direction, you’re going to feel a kick in the opposite direction. Ready to see these ideas in action? Let’s go…


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Look Out Below!

Thursday September 10, 2009

If you jump out of an airplane, how fast would you fall? What’s the greatest speed you would reach? Let’s practice figuring it out without jumping out of a plane.


This experiment will help you get the concept of velocity by allowing you to measure the rate of fall of several objects. It’s also a great experiment to record in your science journal.


First, you’ll need to find your materials:


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G-Force

Thursday September 10, 2009

A common misconception in science is that centrifugal and centripetal force (or acceleration) are the same thing. These two terms constantly throw students into frenzy, mostly because there is no clear definition in most textbooks. Here’s the scoop: centripetal and centrifugal force are NOT the same thing!


This experiment is mostly for Advanced Students, but here’s a quick lesson you can do with your younger students…


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Balloon Racers

Thursday September 10, 2009

We’re going to experiment with Newton’s Third law by blowing up balloons and letting them rocket, race, and zoom all over the place. When you first blow up a balloon, you’re pressurizing the inside of the balloon by adding more air (from your lungs) into the balloon. Because the balloon is made of stretchy rubber (like a rubber band), the balloon wants to snap back into the smallest shape possible as soon as it gets the chance (which usually happens when the air escapes through the nozzle area). And you know what happens next – the air inside the balloon flows in one direction while the balloon zips off in the other.


Question: why does the balloon race all over the room? The answer is because of something called ‘thrust vectoring’, which means you can change the course of the balloon by angling the nozzle around. Think of the kick you’d feel if you tried to angle around a fire hose operating at full blast. That kick is what propels balloons and fighter aircraft into their aerobatic tricks.


We’re going to perform several experiments here, each time watching what’s happening so you get the feel for the Third Law. You will need to find:


  • balloons
  • string
  • wood skewer
  • two straws
  • four caps (like the tops of milk jugs, film canisters, or anything else round and plastic about the size of a quarter)
  • wooden clothespin
  • a piece of stiff cardboard (or four popsicle sticks)
  • hot glue gun

First, let’s experiment with the balloon. Here’s what you can do:


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Rocket Ball Launcher

Thursday September 10, 2009

This is a satisfyingly simple activity with surprising results. Take a tennis ball and place it on top of a basketball… then release both at the same time.


Instant ball launcher!


You’ll find the top ball rockets off skyward while the lower ball hit the floor flat (without bouncing much, if at all). Now why is that? It’s easier to explain than you think…


Remember momentum? Momentum can be defined as inertia in motion. Something must be moving to have momentum. Momentum is how hard it is to get something to stop or to change directions. A moving train has a whole lot of momentum. A moving ping pong ball does not. You can easily stop a ping pong ball, even at high speeds. It is difficult, however, to stop a train even at low speeds.


Mathematically, momentum is mass times velocity, or Momentum=mv.


One of the basic laws of the universe is the conservation of momentum.  When objects smack into each other, the momentum that both objects have after the collision, is equal to the amount of momentum the objects had before the crash. Once the two balls hit the ground, all the larger ball’s momentum transferred to the smaller ball (plus the smaller ball had its own momentum, too!) and thus the smaller ball goes zooming to the sky.


Materials:


  • two balls, one significantly larger than the other
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Impulse & Momentum

Thursday September 10, 2009

This experiment is for advanced students.It’s time for the last lesson of mechanics. After all this time, you now have a good working knowledge of the rules that govern almost all movement on this planet and beyond!! This lesson we get to learn about things crashing into one another!! Isn’t physics fun?! We are going to learn about impulse and momentum.
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Circular Motion

Wednesday September 9, 2009
This experiment is for advanced students. Circular motion is a little different from straight-line motion in a few different ways. Objects that move in circles are roller coasters in a loop, satellites in orbit, DVDs spinning in a player, kids on a merry go round, solar systems rotating in the galaxy, making a left turn in your car, water through a coiled hose, and so much more.

Velocity is always tangent to the circle in the direction of the motion, and acceleration is always directed radially inward. Because of these two things, the acceleration that arises from traveling in a circle is called centripetal acceleration (a word created by Sir Isaac Newton). There’s no direct relationship between the acceleration and velocity vectors for a moving particle.

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Detecting the Gravitational Field

Friday August 14, 2009

Ok, sort of a silly experiment I admit. But here’s what we’re going for – there is an invisible force acting on you and the ball. As you will see in later lessons, things don’t change the way they are moving unless a force acts on them. When you jump, the force that we call gravity pulled you back to Earth. When you throw a ball, something invisible acted on the ball forcing it to slow down, turn around, and come back down. Without that force field, you and your ball would be heading out to space right now!
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Detecting the Magnetic Field

Friday August 14, 2009

Remember, there are four different kinds of forces: strong nuclear force,
electromagnetism, weak nuclear force, and gravity. There are also four basic force fields that you come into contact with all the time. They are the gravitational field, the electric field, the magnetic field, and the electromagnetic field. Notice that those four force fields really only use two of the four different kinds of force: electromagnetism and gravity. Let’s take a quick look at what causes these four fields and what kind of objects they can affect, starting with the magnetic field.


Here’s what you need:
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The Electromagnetic Field

Friday August 14, 2009

iStock_000002030797XSmallThe electromagnetic field is a bit strange. It is caused by either a magnetic field or an electric field moving. If a magnetic field moves, it creates an electric field. If an electric field moves, it creates a magnetic field.


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Detecting the Electric Field

Friday August 14, 2009

You are actually fairly familiar with electric fields too, but you may not know it. Have you ever rubbed your feet against the floor and then shocked your brother or sister? Have you ever zipped down a plastic slide and noticed that your hair is sticking straight up when you get to the bottom? Both phenomena are caused by electric fields and they are everywhere!


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Flying Paper Clip

Friday August 14, 2009

Have you ever been close to something that smells bad? Have you noticed that the farther you get from that something, the less it smells, and the closer you get, the more it smells? Well forces sort of work in the same way.


Forces behave according to a fancy law called the inverse-square law. To be technical, an inverse-square law is any physical law stating that some physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity.


The inverse-square law applies to quite a few phenomena in physics. When it comes to forces, it basically means that the closer an object comes to the source of a force, the stronger that force will be on that object. The farther that same object gets from the force’s source, the weaker the effect of the force.


Mathematically we can say that doubling the distance between the object and the source of the force makes the force 1/4th as strong. Tripling the distance makes the force 1/9th as strong. Let’s play with this idea a bit.


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Force-full Cereal

Friday August 14, 2009

cerealDid you know that your cereal may be magnetic? Depending on the brand of cereal you enjoy in the morning, you’ll be able to see the magnetic effects right in your bowl. You don’t have to eat this experiment when you’re done, but you may if you want to (this is one of the ONLY times I’m going to allow you do eat what you experiment with!) For a variation, pull out all the different boxes of cereal in your cupboard and see which has the greatest magnetic attraction.


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Building Bridges

Friday August 14, 2009

What keeps building from toppling over in the wind? Why are some earthquake-proof and others not? We’re going to look at how engineers design buildings and bridges while making our own.


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Net Forces

Friday August 14, 2009

It is very rare, especially on Earth, to have an object that is experiencing force from only one direction. A bicycle rider has the force of air friction pushing against him. He has to fight against the friction between the gears and the wheels. He has gravity pulling down on him. His muscles are pushing and pulling inside him and so on and so on.


Even as you sit there, you have at least two forces pushing and pulling on you. The force of gravity is pulling you to the center of the Earth. The chair is pushing up on you so you don’t go to the center of the Earth. So with all these forces pushing and pulling, how do you keep track of them all? That’s where net force comes in.


The net force is when you add up all of the forces on something and see what direction the overall force pushes in. The word “net”, in this case, is like net worth or net income. It’s a mathematical concept of what is left after everything that applies is added and subtracted. The next activity will make this clearer.


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Barrel Roof

Friday August 14, 2009

This roof can support over 400 times its own weight, and you don’t need tape! One of the great things about net forces is that although the objects can be under tremendous force, nothing moves! For every push, there’s an equal and opposite pull (or set of pulls) that cancel each other out.


This barrel roof is an excellent example of how to the forces all cancel out and the roof stands strong (hopefully!) If you have trouble with this experiment, just use cardstock or other heavy weight paper instead of regular copy paper.


Here’s what you need:
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A Weighty Issue

Wednesday August 12, 2009

This lesson may give you a sinking sensation but don’t worry about it. It’s only because we’re talking about gravity. You can’t go anywhere without gravity. Even though we deal with gravity on a constant basis, there are several misconceptions about it. Let’s get to an experiment right away and I’ll show you what I mean.


If I drop a ping pong ball and a golf ball from the same height, which one hits the ground first? How about a bowling ball and a marble?


Here’s what you need:


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Forever Falling

Wednesday August 12, 2009

If I toss a ball horizontally at the exact same instant that I drop another one from my other hand, which one reaches the ground first? For this experiment, you need: Please login or register to read the rest of this content.


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Fast Ball

Wednesday August 12, 2009

You have just taken in a nice bunch of information about the wild world of gravity. This next section is for advanced students, who want to go even deeper. There’s a lot of great stuff here but there’s a lot of math as well. If you’re not a math person, feel free to pass this up. You’ll still have a nice understanding of the concept. However, I’d recommend giving it a try. There are some fun things to do and if you’re not careful, you might just end up enjoying it!


Here’s what you need:


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Tracking your Treads

Monday August 10, 2009

Now let’s talk about the other ever present force on this Earth, and that’s friction. Friction is the force between one object rubbing against another object. Friction is what makes things slow down.


Without friction things would just keep moving unless they hit something else. Without friction, you would not be able to walk. Your feet would have nothing to push against and they would just slide backward all the time like you’re doing the moon walk.


Friction is a very complicated interaction between pressure and the type of materials that are touching one another. Let’s do a couple of experiments to get the hang of what friction is.
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What a Drag!

Monday August 10, 2009
There’s a couple of misconceptions that I’d like to make sure get cleared up here a bit. I don’t want to go into too much detail but I want to make sure to mention these as they may be important as you go deeper into your physics education.

First, friction is not a fundamental force. Friction is actually caused by the elemental force of electro-magnetism between two objects.

Secondly, friction isn’t “caused” by the roughness or smoothness of an object. Friction is caused by two objects, believe it or not, chemically bonding to one another. Scientists call it “stick and slip”.

Think about it this way. When you pull the wood in this experiment, notice that the force needed to get the board moving was more then the force was to keep it moving. The surface you were pulling the board on never got any rougher or smoother, it stayed pretty much the same.

So why was it harder to get the board moving?

When the board is just sitting there, the chemical bonds between the board and the surface can be quite strong. When the board is moving however, the bonds are much weaker. Here's what you need:

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Stick & Slip

Monday August 10, 2009

Friction is everywhere! Imagine what the world would be like without friction! Everything you do, from catching baseballs to eating hamburgers, to putting on shoes, friction is a part of it. If you take a quick look at friction, it is quite a simple concept of two things rubbing together.


However, when you take a closer look at it, it’s really quite complex. What kind of surfaces are rubbing together? How much of the surfaces are touching? And what’s the deal with this stick and slip thing anyway? Friction is a concept that’s many scientists are spending a lot of time on. Understanding friction is very important in making engines and machines run more efficiently and safely.


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Exponential Friction

Monday August 10, 2009
expfrictionFind a smooth, cylindrical support column, such as those used to support open-air roofs for breezeways and outdoor hallways (check your local public school or local church). Wind a length of rope one time around the column, and pull on one end while three friends pull on the other in a tug-of-war fashion.

Experiment with the number of friends and the number of winds around the column. Can you hold your end with just two fingers against an entire team of football players? You bet!

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Bearings

Monday August 10, 2009

Stand on a cookie sheet or cutting board which is placed on the floor (find a smooth floor with no carpet). Ask someone to gently push you across the floor. Notice how much friction they feel as they try to push you.


Want to make this job a bit easier?


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Hovercraft

Monday August 10, 2009

hovercraftHovercraft transport people and their stuff across ice, grass, swamp, water, and land. Also known as the Air Cushioned Vehicle (ACV), these machines use air to greatly reduce the sliding friction between the bottom of the vehicle (the skirt) and the ground. This is a great example of how lubrication works – most people think of oil as the only way to reduce sliding friction, but gases work well if done right.


In this case, the readily-available air is shoved downward by the hover motor and the skirt traps the air and keeps it inside, thus lifting the vehicle slightly. The thruster motor’s job is to propel the craft forward. Most hovercraft use either two motors (one on each side) for steering, or just one with a rudder that can deflect the flow (as your project does).


The first hovercraft were thought about in the 1800s, but it wasn’t until the 1950s that real ones were first tested. Today, the military use them for patrolling hard-to-drive areas, scientists use them for swamp research studies, and businesses use them to transport toys and food across rough and icy areas. Scientists are already planning future ACVs to use magnetic levitation in addition to the air power… but it’s still on the drawing board.


Are you ready to make your own? We have TWO different models to choose from. Click this link for the Easy Balloon-Powered Model, or keep reading below for the advanced version.
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Buzzing Hornets

Monday July 27, 2009

hornet1Sound is everywhere. It can travel through solids, liquids, and gases, but it does so at different speeds. It can rustle through trees at 770 MPH (miles per hour), echo through the ocean at 3,270 MPH, and resonate through solid rock at 8,600 MPH.


Sound is made by things vibrating back and forth, whether it’s a guitar string, drum head, or clarinet. The back and forth motion of an object (like the drum head) creates a sound wave in the air that looks a lot like a ripple in a pond after you throw a rock in. It radiates outward, vibrating it’s neighboring air molecules until they are moving around, too. This chain reaction keeps happening until it reaches your ears, where your “sound detectors” pick up the vibration and works with your brain to turn it into sound.


You can illustrate this principle using a guitar string – when you pluck the string, your ears pick up a sound. If you have extra rubber bands, wrap them around an open shoebox to make a shoebox guitar. You can also cut a hole in the lid (image left) and use wooden pencils to lift the rubber band off the surface of the shoebox.


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Harmonicas

Monday July 27, 2009

Your voice is a vibration, and you can feel it when you place a hand on your throat when you speak. As long as there are molecules around, sound will be traveling though them by smacking into each other.


That’s why if you put an alarm clock inside a glass jar and remove the air, there’s no sound from the clock. There’s nothing to transfer the vibrational energy to – nothing to smack into to transfer the sound. It’s like trying to grab hold of fog – there’s nothing to hold on to.


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BONUS! Nine Sonic Vibes Experiments to Mystify Your Kids

Tuesday June 30, 2009

Kazoo

Cut a piece of tissue paper the same length as a plastic comb (make sure the comb’s teeth are close together). Fold the tissue paper in half, wrapping it around the teeth of the comb.  Place it lightly between your lips and hummm… you’ll feel an odd vibrational effect on your lips as your kazoo makes a sound! You can try different papers, including waxed paper, parchment, tracing paper, and more!


Poppers

Cut the neck off a small balloon (balloons made for water bombs work well) and stretch it over the opening of a film canister. Pinch the drum head and pull up before you release – POP! You can change the pitch by adjusting the stretch of the drum head.
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Ten Static Electricity Experiments to Mystify Your Kids

Saturday March 7, 2009

Plasma ball centerThe smallest thing around is the atom, which has three main parts – the core (nucleus) houses the protons and neutrons, and the electron zips around in a cloud around the nucleus.


The proton has a positive charge, and the electron has a negative charge. In the hydrogen atom, which has one proton and one electron, the charges are balanced. If you steal the electron, you now have an unbalanced, positively charge atom and stuff really starts to happen. The flow of electrons is called electricity. We’re going to move electrons around and have them stick, not flow, so we call this ‘static electricity’.


These next experiments rely heavily on the idea that like charges repel and opposites attract. Your kids need to remember that these activities are all influenced by electrons, which are very small, easy to move around, and are invisible to the eye.
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