PVC Rocket

All rockets are powered by explosions.  All explosions are rapidly expanding gases.  Usually they’re expanding because they’re burning, but not always. In the PVC rocket launcher the propellant is burning hairspray. The Science Behind the PVC Rocket In the rocket we built, the hair spray inside the tube is set on fire.  Hairspray is tiny particles suspended in the air, it is in aerosol form.  This means each little particle is mixed with lots of air.  And each little particle is also very inflammable, it will burn with the slightest provocation.  When the hairspray burns the chemicals in the hairspray, which usually includes some form of alcohol, mixes with oxygen and forms carbon dioxide gas.  The carbon dioxide gas formed is in much greater concentration than that of the surrounding air.  That means the pressure inside the launching tube is much greater than the pressure outside.  The easiest way for … click to read more

Heat Conduction Experiment

Heat conduction is when heat is transferred through molecular agitation without any movement of the object as a whole.  Essentially, as a molecule heats up, it moves and shakes quickly, then moves the other nearby molecules, which move and shake in turn.  Bit by bit, heat is transferred through those movin’, shakin’ molecules in a chain reaction.  This may seem complicated, but it’s simple to demonstrate with this heat conduction experiment. Start by putting a pot of water on the hot stove.  Once the water is good and hot (boiling or near boiling), carefully place 3 different spoons in the pot – one metal, one plastic or rubber, and one wooden spoon. The next step is to make a prediction about what will happen of you place a little pat of butter on each of the spoons.  Have the kids write down their predictions. Here is a scientific method experiment … click to read more

Drumming On Your Ears

We can hear because of sound waves bouncing off our ear drums.  Vibrations in the air travel down our auditory canal and hit against the tympanic membrane, also known as the ear drum.  From there the vibrations are passed on to malleus and the incus, both bones.  They then hit against the smallest bone in the human body, the stapes.  These three tiny bones in the ear amplify the sound by about 30 times.  The stapes then vibrates against the fluid filled cochlea which passes the movement on to the nervous system and to the brain where it is interpreted as sound.   Sound Waves On Your Ears Experiment To see how sound can actually create vibrations in a membrane get a wide-mouthed glass bowl and stretch plastic wrap across it very tightly. It must be tight or this will not work. Now toss a few grains of rice into … click to read more

Balloon Rockets and Newton

To teach about Newton’s Third Law, make balloon rockets.  Newton’s Third Law states: For every action there is an equal and opposite reaction.  Think of it this way.  If you were standing on roller blades facing a wall and push off the wall you will roll backward and the harder you push the further you will roll. Balloon Rockets You need a balloon, a straw, tape and string. Blow up the balloon.  While keeping the end of the balloon pinched shut with your fingers, tape the straw to the balloon.  It helps to have two people. Then fish the string through the straw, making sure that the open end of the balloon is facing backward from the way you want the balloon to go. Tie one end of the string to a chair or table leg. Then let the balloon go.  It will zip along the string like a rocket. … click to read more

Energy Conversion

Energy conversion is energy changing from one form to another. Like when the electrical energy in the wires to your house changes to light and heat in your light bulb when you flip the switch. Sunlight changes to energy for growth in a plant. The energy of flowing water can be changed into stored electricity. The energy stored in molecular bonds can be converted to kinetic, heat, sound, and light energy in a firework. Energy moves in chains too. For example the sun gives energy to heat air and water, which create the water cycle and flowing water in rivers, and the flowing water can turn a turbine in a dam, which can generate electricity to light up a light bulb in your house. Every time you change energy to a new form you lose some to heat or friction or sound or something else, your energy use is inefficient. … click to read more

Friction

Friction is the slowing down of a moving object because it is touching another object. Newton said that objects in motion tend to stay in motion and they do. In a vacuum, or in a place with nothing, if an object were put into motion it would never stop. In space objects keep moving at their original speed forever or until they collide with another object. But on earth we have friction to slow us down. Look for places around your house where friction is an issue. Consider cars, bicycles, the bathtub (don’t want to slip), the outside walk when it’s wet or icy, the spinning drum in your dryer, and many more. In some places we want friction and in others we don’t. How do we overcome the friction problems in each of the places you found around your home? Wheels are a way to overcome friction. Think about … click to read more

Inertia

A physics experiment on inertia and Newton's first law.

Inertia is Newton’s first law. It states that an object in motion tends to stay in motion and an object at rest tends to stay at rest.  Inertia is the word we use to explain this phenomenon. Inertia Experiment Get a wheeled toy, like a car or a truck and place an object on top of it, like a penny or lump of clay. Send the car down a short ramp and have it crash into an object at the bottom.  The car will stop, but the penny or lump of clay will shoot forward. Ask your kids questions about it: Why does the clay keep moving when the car stops? Why does the car stop? Does this work no matter the size and speed of the car? (experiment with different conditions) Is this true of real cars out on the road? Why do you think we wear seat belts? … click to read more

Forces

Forces are the effects of objects acting on one another. This might be a breeze stirring a leaf or a jet engine pushing on the air to create a forward thrust.  Or it could be a boffer sword battle.   Brainstorm many different ways to use force: pushing pulling tearing smashing twisting floating sinking stopping accelerating changing directions bouncing spinning Now try some of them out: Smashing Use dough or putty of some kind and squash a ball of it. Where did the force to smash the ball come from? Pushing Push an object like a basket full of books or crayons across a counter top. What direction did the force come from? Where did the force come from? What other forces were acting on the ball? (friction, the counter top pushing up so the object doesn’t fall, air pushing down, gravity pulling down) Bouncing Bounce a ball on a hard … click to read more

The Science of Sledding

The top of the hill. Anticipation. The ride down. Stimulation and Trepidation. The bottom of the hill. Satisfaction.  We can learn some physics principles through the science of sledding. These three stages, the top, the ride down, and the bottom, are examples of energy in action. At the top you have potential energy, you have energy stored, just by being a high place from which you can fall or slide down. If you didn’t your sled would just sit there, you would never fall down the hill, instead you would have to push all the way down, no matter how slick or steep the hill. While you are sliding down the hill you still have potential energy, the rest of your ride, but that potential energy is getting less and less as you approach the bottom of the hill. You are gaining more and more kinetic energy as you approach … click to read more