Vinegar and Baking Soda Rocker Experiment No.2 /2016

Class 1101 Jirayu Mahatongkum 5861039 Khaboonpak Sakityanyong 5861051

Nattapong Vongchankit 5861073 Thitasit Likitkajorn 5861169 Pholawat Tangsatit 5861100

General Physics

Mahidol University International Demonstration School Lab Instructor – P’Win / P’Sharick

Wednesday February 9th 2016 10.15 – 11.15 Lecture Instructor – Gopinath Subramanian

Objective

To create the rocket from daily life used items and launch it 20 meters away into the target. The rocket should be well designed in both aerodynamics and decoration. The fuel of the rocket is required to be vinegar and baking soda reaction with the minimized amount for the best distance covered. Materials

1. Vinegar(5%) 2. Baking Soda 3. PVC (2 x 4m, 6 x 90degree joint, 2 x 3 cross joint) 4. Duct Tape 5. Color Spray (For decoration) 6. Tissue Paper 7. Plastic Bottle (Around 1.5 liters) 8. Stone (Small size for the head) 9. Cork (Recommended Rubber) 10. Polypropylene Board 11.Glue Gun

Set-up First, we drew the wrapped sketch of our rocket for preparing the materials

and design.

We listed out the materials we needed. The method was separated into 3 main sections: Building Rocket, Building Launcher ,and Launching Tutorial.

Building Rocket

In this step, we used PP board, glue gun, duct tape, plastic bottle, color spray ,and stone. We emptied the bottle and labeled 3 sides for the wings.

Side view both sides

Top view

This rocket had 3 wings: 2 aeroplane types side wings and 1 vertical stabilizer(known as tail). The dimension of all wings was equal in parallelogram shape. We cut them out of the PP board into 6 pieces, 2 for each wings. With length of 15 centimeters and 6 centimeters width, also we used interior angle of 135 degree for parallelogram.

After we cut off all of them. We put two pieces of PP board together and wrapped them round with duct tape, finally we got 3 nice pieces of wings.

We used glue gun to stick the wing to the labelled point. Side would stretch out like an airplane wing. After the glue was dried, we sticked them with duct tape for strength.

We put some rock on top of the rocket and wrapped with duct tape.

Decoration was our last step for Building Rocket. This was just for good design only, no impact on the accuracy.

Building Launcher

We prepared the materials first. In this section, we would need 4 meters PVC 2 pipes, 6 90 degrees joints ,and 2 3 cross joints.

This was our simple launcher.

We built rectangle PVC connected with 90 degree joints. On one length, we cut into half and used 2 cross joints as the base for launcher arms. We had to put two cross joint as closed as we could so the arms didn’t leave much space between each of them.

We measured and cut out the PVC into shape. The degree of arms should be 40 degree for maximum distance. The distance of arms was 1.20 meters for extended the way of launching. After we measured the angle and put on the arms. We inserted 2 more 90 degree joints at the end of the arms and measured the length for the arms horizontal basement. We cut 2 more pipe according to our measurement.

Launching Tutorials

We set the launch base into position and aimed the base into direction we needed. For the fuel, we used tissue paper, duct tape, baking soda, cork ,and vinegar. We poured 300 ml of vinegar into the rocket. Then, we created the actual fuel for the experiment. We used two pieces of tissue paper and put overlapped for a little in vertical way. Then, we wrapped to connect and avoid leaking. Especially the head and the top should be wrapped carefully so baking soda would not react with vinegar before the launching session.

Lastly, we slowly inserted the fuel into the bottle. This step should be done carefully so there was no reaction before the time. After putting most part of the fuel into the bottle, we put the cork and applied pressure as much as we could. This was the most important part to keep the pressure as much as we could. Finally, we slowly flipped and placed the rocket son the base. Shaking was alternative method if fast reaction was needed.

Introduction The rocket is pushed for the length of time that the cork pushes into the

ground and then a few more inches after it comes off. After that there is no more push. So really it is less like a rocket and more like a bullet or a ball being thrown. Projectiles that don’t have their own energy source accelerate only while they are in contact with their launcher. This is an example of Newton’s second law: an object will accelerate according to how much force is put on it, and when the force is no longer there, it will no longer accelerate. The stomp rocket is going as fast as it will ever go just as it comes off the end of the tube. Real rockets will continue to accelerate as long as there is hot gas escaping from their rocket nozzles. You can divide the motion of the rocket into vertical and horizontal elements. In physics, these are called vectors. If you think about only the vertical element – a flight straight up and straight down – it is easier to understand the motion. As soon as the cork leaves the rocket it has no more force pushing it up, but gravity is always pulling it down. The rocket begins to slow and continues slowing until it stops at the top of its path. Then, it turns around and begins accelerating again toward the ground, this time powered entirely by gravity. If there were no air resistance on the rocket, the speed of the rocket when it hits the ground would be exactly what it was when it left the ground on its way up.

Discussion of Physics Concepts

Measurements For the total mass of rocket, at first we had 230 grams. After a first trial, we

realized that the rocket was too heavy, which impacted the flight to fall earlier according to simple principles of gravitational. So then we minimized the weight to reduce the gravity force and increased the result of driving force. We finally got 170 grams of airplane.

The amount of reactants were calculated through the reaction between baking soda and vinegar as aHCO CH COOH CO a CH COO ON 3 + 3 = 2 +N +

3− +H 2

.(Marie, n.d.) We used 300 ml of 5% vinegar or 15 grams and 20 grams of baking soda. It came from the best trial. After we recorded, we brought the mass of each reactants to find the molar mass. From this calculation, we would know that the amount of reactants creating the most efficient reaction or not. Newton’s Laws of Motion

Newton’s First Law of Motion 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. In this case the rocket was acted on by gravity so the rocket was pulled down toward the ground. If there was no force to act on the rocket after it was launched it will still keep moving with the same speed and the same direction as it was launched.

The rocket is pushed because the cork pushes itself against the ground and a

little bit after the cork falls off then there is no more push afterward. This is more like a ball being thrown than a rocket. After the rocket loses contact with the launcher they don’t have energy source to accelerate itself. This is an example of Newton’s second law which stated that an object will accelerate according to how much force is put on it, and when the force is no longer there, it will no longer accelerate. It can’t goes faster than when it accelerates. Real rockets will continue to accelerate as long as there is hot gas escaping from their rocket nozzles.

Newton's Third Law of Motion states that for every action done by a force,

there is an equal and opposite reaction by another force. Forces always occur in pairs; one force is called an action force and the other is called the reaction force. The action force is caused by carbon dioxide from the reaction between vinegar and baking soda. The reaction gas causes pressure to build inside the soda bottle, eventually pushing the cork from its mouth. A result of this action is the movement of the soda bottle in the opposite direction. This movement is caused by the reaction force that stems from the original action. There are many other examples

of force pairs in everyday life. When you walk, your feet push on the ground with a force. In return, the ground pushes on you with an equal force, propelling you forward. A plate resting on a table exerts a downward force on that table due to gravity. In return, the table exerts an upward normal force on the plate. (Nasa, n.d.)

Linear Motion (Freefall)

Linear motion cannot apply in this experiment due to the rocket to moving

horizontally from the launcher to the target. The concept of free fall is the moving in zero air resistance or when air resistance is negligible. They stated that without resistance, feather and rock will fall at the same time. The air drug is from interacting between shape of object and air molecule. In free falling motion, the object will have constant acceleration rate is around 9.8 meters per seconds if the falling is taken on Earth due to the gravitational field. (Carasco, 2016)

In this experiment, we couldn’t use this concept because the rocket doesn’t

move vertically and air resistance taking action on the rocket, so

The reason ,why rocket doesn’t achieve free fall, is the rocket moving as aeroplane. The force from reaction drives the rocket forwards with the angle of launcher, we create projectile,which will be discussed in the next topic. The rocket with thrust and lifting force is pushed across the the sky in projectile path.

Projectile You can divide the motion of the rocket into vertical and horizontal

elements. In physics, these are called vectors. If you think about only the vertical element – a flight straight up and straight down – it is easier to understand the motion. As soon as the cork leaves the rocket it has no more force pushing it up, but gravity is always pulling it down. The rocket begins to slow and continues slowing until it stops at the top of its path. Then, it turns around and begins accelerating again toward the ground, this time powered entirely by gravity. If there were no air resistance on the rocket, the speed of the rocket when it hits the ground would be exactly what it was when it left the ground on its way up.

It is harder to consider the sideways vector alone because we have no experience living without gravity. If one were to launch this rocket in space where there is no gravity or air, it would accelerate for the length of the PVC, attain its maximum speed, and then continue on with that speed until hitting something. This

is an example of Newton’s first law: objects in motion tend to stay in motion and objects at rest tend to stay at rest. Here on earth, the air that the rocket encounters slows its sideways motion.

The result of these two different vectors of motion is a curved path called a parabola. Everything thrown up from the earth follows a parabola (if you ignore influence from the air). You can see it in ball games, bomb blasts and when throwing a rock. (thePhysicsClassroom, 2016)

Impulse and Momentum

Impulse is the term that qualified of a force acting overtime, calculation by multiplying force with time.

Momentum is the measurement of mass in motion, usually in vector quantity

of kg per meter per second, calculating by mass multiply with velocity. The momentum can be found in every single moving object. It has its conservation as m1v1 + m2v2 = m1v1 + m2v2 or the total momentum before and after any events shall be equal. Shooting a gun is quite a good example from laws of momentum conservation. At first the total momentum is zero ,because there is no motion in both bullet and gun. After we fire, the momentum of bullet and gun should be subtact and equal to the initial momentum due to the different direction. This is possible even both gun and bullet are moving at the different speed. Momentum is determined from mass and velocity so bullet has little recoil

comparing to a bullet ,because gun has more mass which results in less velocity from higher velocity take place in bullet.

Momentum in this rocket experiment can be explained easily. First, the

momentum of rocket is equal to mass of the entire rocket multiple by velocity from the initial session of launching. Second, after a short period, our rocket has released carbon dioxide and other product from the chemical reaction ,which uses vinegar and baking soda as the reactants, with certain velocity in opposite direction of the rocket. In this process, the rocket will lose its weight that raise the whole velocity of the rocket. However, the total momentum of the system declined from the gravitational force acting over time. (It is called simply impulse, as a net external force on a system multiplied by time ,and equals to the rate of change of momentum.) With the force accelerates the system and loses its own mass. As well as the action-reaction force acting from the launcher. Those force drives away the rocket to the target while losing a little velocity from negative force from gravity. (Boundless,2016) This diagram is showing the concept of momentum on rocket.

Energy (Work, Power, KE,

PE) KE and PE

Energy ,like other physics term, has conservation laws. According to the laws, energy can neither be created or destroyed. It just changes the form. So in the rocket system, the total energy should be equal in the entire experiment ,but it is not closed system so some of energy leak out in different forms. In this experiment, only three types of energy involved: kinetic energy, potential energy and chemical energy.

Kinetic energy is the energy in moving object and can be easily calculated by knowing mass of the rocket and velocity. This is the equation for kinetic energy, KE = ½ mv^2. However, we cannot measure the exact velocity of our rocket

system so it is impossible to find the total kinetic energy in joule as the rocket taking it flight.

Potential energy is stored inside the rocket while holding its position above the ground. It is simply meant the amount of energy can be released from this object above the ground if this object is falling down. If the object is on the ground, the total potential energy will be zero. The equation of potential energy is PE = mgh.

Kinetic energy and potential energy are inversely proportional. The decline of potential energy is occurred from moving down ,but in this movement kinetic energy will raise because of the motion. So the increasing in each energy, the other energy will be decreasing at the same amount.

r For the last energy, chemical energy, it is the energy stored in the chemical

bonds inside any chemical. After some certain condition, those chemical is released into other forms.

At it pre-launching session, there are no kinetic energy or potential energy

,but maximum of chemical energy. After the launching to its highest point, chemical energy declines ,but both kinetic energy and potential energy raise. Some point at its maximum velocity, kinetic energy is in highest volume. When the rocket reaching highest point, potential energy is in maximum point ,where no kinetic energy and chemical energy. Then, the rocket starts to fall down in projectile pattern while kinetic energy is constant, the potential energy is

diminishing. On the last landing point, there are no any energy of those three. (philsrocket.org,2016)

Work

The work done on the body of object is when the object with certain force of F moving in certain distance or D ,so work done is equal to force multiple by distance. However, the force applies on our rocket are different in the vary of time but we ensure that the greater force of work done would be occurred longer distance as the following graph.

Power

The power is the rate at which work is done. So the power of the rocket is the work done amount divided the time interval, which power is difficult to find due to many problems of measurement in each points. Discussion of Design

We had 3 main states of our rocket ,but in every state, we agreed to use big

bottle for holding more fuel in the rocket. Our first rocket had 4 small wings at the end of the bottle.

This rocket was the first that we did. We unsuccessfully launched it because at the early of experiment, we didn’t notice involving of cork so the pressure were not trapped and leaking out all the time. With this reason, all of trial on that day were failed due to no cork fitting in the bottle.

Unfortunately, we changed the rocket before we launched with cork. Our

new rocket was built similarly to an aeroplane. We had 2 long wings and stabilizer at the back.

With this shape, we hoped the rocket would fly and cut through the sky like

aeroplane. The wing would increase lifting force and cut through air resistance, enhancing the movement of the rocket. So as long as the applied force are acting on the rocket forwards, the rocket will be able to sustain it position on its flight.

Lastly, we realized unnecessarily of the wings and stabilizer. So we decided to get it out reducing the mass. Finally, we created torpedo shape of rocket which was very stable and straight. With a circular shape of our rocket and high force acted on it, the rocket can be able to move straightly through the air as the torpedo cut through the water and hit the ship.

Data

No. Rocket Mass(g) Baking Soda(g) Vinegar(ml) Angle Distance(m)

1 230.0 25.2 300 40 14

2 172.5 18.4 300 40 13

3 170.1 20.2 250 40 19

4 170.1 20.1 300 40 20

5 170.1 20.1 300 40 0

6 170.1 20.1 300 40 27

7 170.1 20 250 40 19 Analysis of Data

From the data above, the perfect amount of baking soda is 20 grams and vinegar is around 250 - 300 ml. Mass is also very important to the distance of the flight. We decrease the mass of the rocket and it seems to be effective comparing from first and third experiment, 5 meters are added for the total distance. Not just the reducing mass but the distribution of mass also impacts the lifting process. At the second time, we reduce all of the head mass and it results in fewer distance because the rocket has rectangle face and the body is heavy in the end so the wind can easily destroy the flight.

Conclusion

From this experiment in the aspect of physics, the rocket are able to launch and land ,but we have several mistake in both design of the rocket and calculation so that the flight are not successfully landing on the target. Many theories are involved in the design, momentum , aerodynamics and projectile for essential calculation. With more advanced tools and calculation, we can take this experiment furthermore. Recommendation

There are 4 main problems to issue in this experiment. The chemical

amounts should be calculated perfectly and matched to the mass of the rocket as the it uses different force to drive different bodies of mass. The design of the whole body, the rocket must be organized enough so that it can fly across to the target. The base is also very important in this experiment. The length of the arm should be long enough for supporting the pre-launching. It should have some kind of solid wall to block the end of the bottle creating the action-reaction force. Last issue is the wing, it is the most external factor that take most effect in every kind of flying stuff. So we suggest to take the experiment in clear and soft season as we will create the equal factor and make the entire experiment stable.

We encourage the experiment to be more official by using advanced

measurement tools. With those tools, we will be able to calculate varies of physics theories such as energy or velocity.

References Marie, A. (n.d.). What Is the Equation for the Reaction Between Baking

Soda and Vinegar? Retrieved at 21 February 2017, from http://chemistry.about.com/od/madscientistlab/a/fizzypotion.htm

Nasa(n.d.). Newton’s Law of Motion. Retrieved at 26 February 2017, from https://www.grc.nasa.gov/www/k-12/airplane/newton.html

Carasco, J. (2016). Free fall equation. Retrieved at 26 February 2017, from http://www.introduction-to-physics.com/free-fall-equations.html

thePhysicsClassroom (2016). What is Projectile?. Retrieved at 26 February 2017, from http://www.physicsclassroom.com/Class/vectors/u3l2a.cfm

Boundless(2016).Rocket Propulsion, Changing Mass, and Momentum. Retrieved at 26 February 2017, from https://www.boundless.com/physics/textbooks/boundless-physics-textbook/linear-momentum-and-collisions-7/rocket-propulsion-71/rocket-propulsion-changing-mass-and-momentum-302-11258/

Philsrocket.org (2016). Physics of Rocket Flight. Retrieved at 26 February 2017, from http://www.philsrockets.org.uk/physics.pdf