Ideal Water Volume


The Problem: Newton’s 2nd law. F = MA Our rockets produce an upwards force by expelling air and water out of the bottle nozzle. According to the law, the greater (more massive) the gas that is expelled and the faster it accelerates out (determined by how much air can be compressed in the bottle) of the engine, the greater the force or thrust.

More air in engine, more acceleration (good) = Less water in engine, less mass (bad)

We need a happy medium

Less air in engine, less acceleration (bad) = More water in engine, more mass (good)

Air, a gas, can easily be compressed.

Water, a liquid cannot be easily compressed

The Question: What ratio of compressed air to water would create the most thrust for our rockets?

Your Hypothesis:

The Experiment:

1.  As a group, we will launch 25 “naked” bottles with varying amounts of water in them.

2.  Because “naked” bottles tend to tumble and are susceptible to the wind, we will set a basketball on top of each rocket. Newton’s 3 laws of motion will send that basketball almost straight up. We will gauge the height and hang time by the basketball.

3.  We will use stopwatches to measure the hang time and sextants (with a little trig) to calculate the basketballs apogee (highest point)

4.  One designated person will record all hang times and sextant angles. Copies of this data will be given to you the next day.

5.  You will need to organize this data into 2 neat tables. (One table for hang-time and one for the angles/height, you must convert the sextant angle to a height!)

·  Think, how many columns and rows does each table needs? Plan ahead and be neat!

·  You only need to record the average hang-times and angles/heights in your data tables.

·  The average angles will need to be converted into a height. (Use our baseline of 30 meters and your tangent table.)

·  Provide informative heading cells and a descriptive title for each table.

6.  Create 2 line graphs from the tables of information.

·  Independent variable (what was tested) on the horizontal axis, dependent variable (what was measured) on the vertical.

·  Title each axis and give each graph a descriptive title.

7.  Study your graphs and write a conclusion below.

·  Restate you original hypothesis.

·  State whether your hypothesis was accepted or rejected and support it with data.

·  Clearly state how much water you will use in your rocket

·  Discuss possible errors in our data collection.