Rocket Lab Report

Matthew Wong and Andrew Romero

Intro

The bottle rocket experiment demonstrates basic Newtonian physics. The rocket demonstrates real-life applications of many laws and formulas. Kinematics and projectile motion are applied in this experiment, as the rocket is a projectile launched in the air by the theory that every action has an equal and opposite reaction.

The motion of the rocket can be found using kinematics. Acceleration = final velocity (vf) – the initial velocity (vi) / change in time (Δt). In addition, (vf)2= (vi)2 + 2ad. These equations calculate the rocket’s highest point, assuming initial velocity is 0 m/s and having measured vf. Final position (y) = initial position (yi) + initial velocity (vi) * time + (½)*acceleration*time2.

Moreover, this multi-stage experiment also includes impulse (i) and momentum (p). Impulse = Force*Δtime. Thus, because impulse is change of momentum, Δp = Force*Δtime. The second formula is p = mass*velocity. Combining the two formulas, m*Δv = F*Δt. F = (m*Δv)/(Δt) is the average force of the rocket.

Lastly, the rocket’s force and acceleration are caused by the pressurized air expelling water from the rocket, creating an opposite reactionary force. Newton’s Third Law of Motion states that every force has an equal and opposite force: pushing out the water pushes the rocket upwards.

Materials

• 2 x 2-Liter bottles
  
  
• Poster board
  
• Duct tape
  
• 10 feet of String
  
• Hard paper (construction paper or cardstock)
  
• 6-10 Cotton Balls
  
• Plastic bag
  
• Bubble wrap
  
• Trash bag
  
• Scissors
  
• Water: H₂O

Procedure

1. Measure and cut out 3 parallelograms for the fins of the rocket.
2. Take a soda bottle and unscrew the cap. This is going to be the part of the rocket that separates.
3. Cut the first bottle into thirds. The top third with the neck of the bottle is the head of the rocket.
4. Tape the fins evenly sticking out of the second bottle. Make sure they are evenly distributed.
5. Next, cover the fins with duct tape for decoration and to make them water-resistant.
6. Make a cone of paper and tape it around and onto the separate piece of the rocket (from step 3)
7. Cut 4 lengths of string of equal length out of a 10-foot string.
8. Take a trash bag and cut off the 4 edges, so that it becomes two squares. Put one of these squares to the side.
9. Cover the 4 corners with tape, for easy hole-punching.
10. Use something sharp to punch holes in the 4 corners.
11. Thread string through these holes, typing and taping the ends down to secure the string.
12. Tie the other ends of all 4 strings to the detachable head of the rocket. This is the parachute.
13. Cover the egg in bubble wrap, and place in a bag with 6 cotton balls.
14. Place the bag in the head of the rocket.
15. Put the head on the rocket, making sure to place the parachute so that the strings are not tangled.
16. The experiment begins: fill the rocket with about 20 mL of water.
17. Place rocket on launcher; making sure the head is on tight but not too tight.
18. Prepare to capture velocity with radar gun.
19. Begin video capture.
20. Pull string to launch rocket.
21. Record data and begin analysis.

Results

 0:08 seconds – showing rocket

• Time of acceleration = 0.28 seconds

• Time to apogee after exhaustion= 2.32 seconds

• Time to hit ground(roof) from apogee = 3.00 seconds

• Velocity = 75 kilometers/hour = 20.83 meters/second

• Mass = 1.2 kilograms

• Height of apogee = 88.87 feet

 

The Third Stage does not apply to this launch because the parachute was not released.

Conclusion

Looking back on this lab, we think our first mistake was not using the phrase, “it’s only rocket science” (instead of “It’s not rocket science.” Haha!). This lab was more than just a lab, it was a chaotic adventure which provided us with a challenge that no one else got, yet still unfortunately applies often to this world. If someone were to ask us, “why’re you still doing this lab? We finished it weeks ago,” we would reply, “well, it landed on the lower roof of the SLC and no one had the 5 minutes it takes to go up to the weight room, and return it to Ms. Roemer, which is what we were told was going to happen. When someone finally realized how easy the task was of retrieving the rocket, they threw it away.” Clearly, we weren’t very happy about the situation, which is something anyone can understand. Although we were upset, we had no excuse for our lack of initiative, this being our greatest flaw when doing this lab. Our lab was saved by high school student and expert-snapchatter Max, who put our first and last launch on his Snapchat story with the caption “They lost they rocket lol.” This video allowed us to find all the times we needed to calculate accelerations and essentially complete the whole lab.

We were very proud of our rocket, for it was insanely durable and was very slick, all thanks to the hours that were put into it. Even though the parachute did not release, the rocket launched over 80 ft. high, only adding to the greatness of the rocket. The only changes we would make to the rocket is whatever changes were needed for a successful release of the parachute. Another thing we could have done is prepare for the worst. If we had assumed that it would take this long for us to complete the rocket, we would have been back on our feet before we even fell. We should have presented the Snapchat video to Ms. Roemer the day the launch happened, allowing us to have finished the lab about two weeks earlier.

        Personally, we took a lot more out of this lab than just perfecting my ability to solve for acceleration, distance, and force. we took away a life lesson that we can guarantee will apply to the future of my academic life. Sometimes, a situation may shift so that the simple 1,2,3, process of getting through it no longer applies, and you need to improvise. Use any resource you have, for there’s no restrictions as to what may help out your situation, which in this case was the lab.