1. What are the two baffles in the "cannon" for?
The two baffles are used to provide more surface area for the cannon so that to increase the rate of the chemical reaction which takes place inside the cannon. Further, the mixing of the fuel with the air inside the cannon would be more complete and as a result, we can get a complete combustion of all the fuel and the cannon ball will go further.
2. What purpose did the shaking of the stack of cans have?
The shaking of the stack of cans was right after the injection of the fuel. Its purpose is to mix the hydrogen gas with the oxygen gas together to maximize the combustion. At the same time, ethanol is spreaded throughout the cannon so that the chance of ignition will be maximized.
3. What kind of Energy transformation occurred during the launch?
The (potential) chemical energy is transformed by the combustion, partially to the kinetic energy of the moving cannonball, partially to the thermal energy while heating the air of the cannon, and small amount to the sound energy and light energy as well. Then the moving cannon's kinetic energy changes into gravitational potential energy as it rises and comes back to kinetic energy as it falls(when the shooting angle is not 0); some of the energy is consumed by the air resistance as well.
4. What other kinds of liquids do you think could be used in place of ethanol?
A lot of other kinds of liquids could be used such as gasoline, alcohol, methanol, propane(after compression it could be liquid), etc. because they are all flammable and can produce lots of energy.
5. Apply one of Newton’s laws that is relative to this experiment. Explain.
Two Newton's laws are relative to this experiment: Accroding to Newton's third law, it states that for every action force, there is an equal and opposite reaction force. When the cannonball is launched forward by cannon, the ball also pushes the cannon backward. This pair of forces are equal and opposite. However, since the cannon is way larger and heavier than the cannonball, it doesn't move a lot.
According to Newton's first law, it states that An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. That's why after the launch, the cannonball is still moving(there is no applied force during this time), it is moving by inertia.
Bibliography:http://www.theteachersguide.com/moredemos.html
http://www.physicsclassroom.com/class/newtlaws/
