Water Bottle Rockets

Table of Contents
Table of Contents 2

3

3
Introduction 4
Aim 5
Hypothesis 5
Variables 5
Apparatus 5
Method 6
Calculations 7
Results 10
Analysis of Results 11
Discussion 12
Conclusion 13
Bibliography 13
Appendices 13
Journal 16

Introduction
A water bottle rocket is essentially that; a bottle modified in the image of a rocket then filled with a select amount of water that is pressurised and launched into the air due to the forces pushing the rocket upwards from the launcher.
When the completed water bottle rocket is sitting on the launcher, the force of the surface of the launcher pushes the rocket up whilst gravity drags it down. As the fluid inside the rocket is pressurized, the forces become unbalanced and release the clamps that are holding back the rocket. The fluid will then be expelled through the small opening at the bottom of the rocket (the bottles nozzle) at a fast rate in one direction and therefore providing a lot of thrust into the other direction, allowing the rocket to propel upward. This force will continue to thrust upwards until the last of the fluid is expelled from the rocket (Moore, 2014).
To increase stability in the rocket, the centre of pressure and centre of mass should be in specific positions on the rocket. The centre of mass is to put simply, a balance point in an object. It is a uniform gravity field that averages the external forces surrounding the object to equalise the forces acting upon it, such as a balance point on a see-saw (HyperPhysics, 2000). The centre of pressure on a rocket is the average location of the pressure, which varies around the surface of an object (NASA, 2010). The fins and aspects of the rocket all contribute to the end position of the centre of mass and pressure and so the centre of mass should be as close to the middle as possible, with also the centre of pressure towards the back of the rocket, which is achieved by