Balloon Powered Car

If you ever wanted to make your own car, this is definitely a project you should check out!

What you'll need:

1 piece of cardboard (4"x6")

1 balloon

1 rubber band

1 straw (preferably bendy)

2 straws (preferably non-bendy)

2 kabob skewers

4 bottle caps

Tape & Scissors as necessary

How to make your car:

1. Take your 4 bottle caps and poke a hole through each cap, just large enough for the kabob sticks to go through. These will become the wheels of your car.
2. Stick one kabob stick through each straw.
3. Put bottle caps on each end of the kabob stick.
4. Tape the straws (with the kabob sticks in them) onto your piece of cardboard. The cardboard will become the base of your car, and your kabob sticks with the "wheels" will allow your car to move!
5. Now, we need to find a way to power your car. To do this, stick the longer end of your bendy straw into the mouth of your balloon, and make it stay with your rubber band.
6. Tape the longer end of the straw (near the bend) onto your piece of cardboard.
7. Now, you can inflate your balloon by blowing into the short end of your straw. When you put your car on the ground and let the air out of your balloon, you can see it travel!

If you want to see a working demo, please check out this video:

Good luck, and have fun!

Rube Goldberg Machine - What's that?

Have you ever seen the band OK GO's music video for their song "This Too Shall Pass"? One of the members of the band used a car to knock down a set of dominos, which leads to more and more convoluted things happening, like balloons being let out of a cage and, in the end, the members of the band being paintballed. Cool, right?

So, why couldn't the band members just set up the paintball guns to shoot automatically? Why all the crazy processes in between? That's the whole concept of the Rube Goldberg machine, named after a cartoonist and inventor who was famous for his silly cartoons where a complicated machine would do a very simple job, like wipe someone's face. The whole concept of a Rube Goldberg machine is to do a simple task in a very complicated way using a chain reaction.

So what's the science behind it? Why does this chain reaction work? Well, the whole process works due to the law of conservation of energy. This law states that energy can not be created nor destroyed, but it can change form. So, when the car hits the domino in the video, the energy from the push that the band member gives the car is transferred to the domino. The energy is too much for the domino to handle, so it falls down and hits the next domino, transferring the energy again. The same energy keeps moving through the system in different forms, like spinning a tire or pulling a string, until it reaches the end and sets off the paintball guns. 

So, what happens at the end of the process? We just said that energy can't just disappear. What happens to the energy once the paintball guns are set off? Over the process, there's some loss of energy due to different factors. Some energy's lost in heat, some due to friction (like when the marbles roll through the frame), and countless other reasons. At the end, the energy transfers to the paintballs, and the last left amount of energy is enough to propel the paintballs at the band members and hit them.

Now that you know the basics of how a Rube Goldberg machine works, it's pretty simple to make one yourself! Pick a simple task, like ringing a bell or dropping a ball in a cup. Then, use any materials that you have lying around (the sillier, the better) and try to put as many steps in your chain reaction as possible. The more transfers of energy, the better! The genius of the Rube Goldberg machine is that you can be as creative as you want to be; there's no wrong way to do it. Good luck!

Hold and Cold Water Science Experiment

Check out this awesome experiment on mixing hot and cold water and see why such an interesting result happens! 
Try this experiment at home to see if it gives you the same results! Make sure you have a parent helping out!