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Water Rockets

Activity: Bottle Rockets and Propulsion

(Before you begin, print out a worksheet to use as you complete the activity.)

Objective:

During the completion of this activity, you will demonstrate science processing skills, an ability to use technological design, and an ability to identify factors that affect motion and forces.

Background Information:

Bottle rockets are excellent devices for investigating "Newton's Three Laws of Motion":

1st Law - A rocket will remain on the launch pad until an unbalanced force is exerted, propelling the rocket upward.

2nd Law - The amount of force depends upon how much air is pumped inside the rocket. You can increase the force further by adding a small amount of water, which increases the mass expelled by the air pressure in the rocket .

3rd Law - Finally, the action force of the air (and water) as it rushes out of the nozzle creates an equal and opposite reaction force propelling the rocket upward.

As with a balloon, air pressurizes the bottle rocket. Adding a small amount of water to the bottle increases the action force. The water expels from the bottle before the air does, turning the bottle rocket into a bigger version of a water rocket toy (available in toy stores).

Extension Activity: In order to learn more about model rockets and how they work, follow these links to information on Flight of a Bottle Rocket, Rocket Aerodynamics, and Forces on a Rocket.

Instructions:

1. You will work in teams to construct two water bottle rockets with empty 2-liter soda bottles. You and your team members must decide (1) on the design you will use as a result of experimenting with the simulators and (2) on the materials you will use for the body, fins, and cone of the rocket (which is placed over the empty 2-liter soda bottle before launch). You will then predict how well your rocket will fly and record your prediction on the worksheet. You may want to customize your rockets by decorating them in some way. An example is shown below:

1. One bottle rocket launcher is needed for the class. While one team launches their rocket, another team can assist them by tracking the rocket, determining how high it flew, and recording the information on a worksheet. (Follow this link to learn how to measure the altitude reached by your rockets: Model Rockets, Measured Altitude.) Then compare your prediction with the rocket's actual performance and compare the flight of your rocket with other rockets. Your final assignment will be a journal entry via email giving details on your design, the comparisons you made, and your conclusions on the reasons for the rockets' performances.
2. You must follow the safety rules launching bottle rockets. Countdowns help everybody to know when the rocket will lift off. Using the launch safety instructions shown below, develop specific launch safety rules through group discussions. In the rules, include how far back observers should stand, how many people should prepare the rocket for launch, and who should retrieve the rocket.

Rubrics:

Use the rubrics shown below as a guide when completing the activity.

Rubric for constructing the bottle rocket and recording observations
(30 points max.)

 Yes No Team carries out assignment criteria 3 points 0 points Team performs testing safely 1 point 0 points Records observations and findings are correct 3 points 0 points Team demonstrates proper science process skills 3 points 0 points Participates in class discussions 5 points 0 points Team kept on task 5 points 0 points Bottle rockets fins aligned properly 3 points 0 points Nose cone straight on rocket 3 points 0 points Team contributes ideas to the class 4 points 0 points

Rubric for email writing (Worksheet Question 13)
(12 points max.)

 Yes No Carries out assignment criteria 3 points 0 points Records observations and findings are correct 3 points 0 points Demonstrates proper science process skills 3 points 0 points Spelling, grammar, and punctuation correct 3 points 0 points

Alternative Recommended Assessments:

1. Evaluate each bottle rocket on its quality of construction. Observe how well the fins align and attach to the bottle. Also observe the alignment of the nose cone at the top of the rocket.
2. Evaluate the design and quality of construction of each bottle rocket by measuring and comparing the altitudes that the rockets reached.