Reflection

       Throughout the design and building process of our balloon car, Claire and I had to go though many challenges, but in the end, we had one of the best balloon cars in the class! We first started building by using a water bottle as the body of the car. The water bottle wasn't an efficient piece to use though because there was a lot of surface area in the front of the bottle which caused the car to slow down. To fix this problem, Claire and I decided to subsitute the water bottle with a flat piece of cardboard, creating less air resistance. 
       Another mistake we made, was when we used four furniture coasters as the wheels. These types of wheels didn't work because they didn't weigh a lot, making our car go airborne. Our solution was by using a heavier set of wheels, which were some old round blocks we found in my basement. These were perfect to use because they applied just enough pressure against the ground to keep the car on the floor and not in the air, but the weight did not slow down the car's acceleration.
       The last idea that did not work very well was when we had the wheels spin around on the stick. The wheels wobbled around on the stick, which made the car turn in little circles. To fix this last situation, we solved it by gluing the wheels to the ends of the sticks. And then we had the sticks spin around inside a small straw that was glued to the bottom of the cardboard. This allowed our car to have rolling friction in a straight line.
       I, Kerri learned a lot throughout the process of creating and testing our balloon car, but if I had to choose the most valuable part of this learning experience was that "If at first you don't suceed, try try again." We had many trial and errors while making the car, but without those problems, we would have never learned from our mistakes. This was a great project to help us understand friction, motion, momentum, force, gravity, etc. while having fun at the same time!

Analysis

a.   Newton's first law of motion states that when an unbalanced force acts on an object, the object accelerates.  In the balloon car lab, one of the forces was the air rushing out of the balloon, causing the car to accelerate forwards.  Gravity and air resistance were the other two forces acting on our balloon car. Gravity caused the car's wheels to slow down and eventually stop spinning while air resistance limited the speed that the car could accelerate with.
b.   Newton's second law of motion states that when an object has a higher mass it takes more force to move the object.  The wheels on our balloon car had a relatively high mass, which made the car heavier, so it took more force to make the car start moving.
c.  Momentum is mass times velocity so if there is a high mass and a high velocity the car will have a greater momentum when it runs out of air and therefore will travel a greater distance without fuel of any kind.  The law of momentum and Newton's second law contradict each other in some ways. One law states that less mass is better and the other states that more mass is better.
d.   Newton's third law of motion states that an action force always has a reaction force. In this case, our balloon car's action force was when the air left the balloon and the reaction force was when the car went forward.  When the car was released, air started rushing out of the balloon hitting the air molecules that where already there, causing those molecules to hit the ones that had just come from inside the balloon and the car went forward.
e.   All three different types of friction act on balloon cars. The air resistance against the car is a kind of fluid friction. While the skewers that we used as axles rubbing against the car, was sliding friction. And the wheels rolling across the floor was an example of rolling friction.

12/6, Trial 2

On Tuesday December 6th, 2011, Kerri and I tested our balloon car for the second time, and it went 19.9 meters! It went further than our first trial, which was 18.2 meters. The car went further because the axles spun in one spot, making the car travel in a straight line and barely turning at all. Although our car went pretty far, Kerri and I believe that our car would have gone further if we were able to blow the balloon up more than what was allowed.

12/5, Trial 1... Almost Perfect!

Yesterday, on December 5th, 2011, Kerri and I had some issues with getting the car to accelerate without turning, but still managed to get a total distance of 18.2 meters.  As you can see in the video below, our car also crashed into a wall as a result of the turning problem.

That, my friends, is how you crash an epic balloon-powered car into a wall!

After analyzing the footage I took of the trial, Kerri and I agreed that I should bring the car home that night to create a way for the axles not to slide back and forth.

Our Final Balloon Car (Design Process)

Claire and I finished our balloon car! (: 

Me with the finished car

The materials we used were:

• Two skinny straws
• One fairly wide straw
• One balloon
• Four round blocks from an old toy chest
• Two skewers
• One square piece of cardboard
• Hot glue gun
• Tape
• Scissors

We did not have to buy any of these items in order to make our cart. We simply used items found around my house. In the end, $0 was spent on car parts for the building process.

Throughout the building process, Claire and I got some help from my parents. My mom helped me find the four wheels to use for the car. And my dad helped me figure out how to make the car accelerate using the wide straw and a balloon. I can't wait to do my first trial of the car. I hope everything goes well!

Today, we found out what we were doing wrong...

We found out that the the cardboard works a lot better than the water bottle. Also, instead of the wheels turning around the stick, we made the stick spin while the wheels stay still. Here are three of our trials with the water bottle car, and one amazing trial with the cardboard car.

The song in this video is called Till I Collapse by Eminem.