1. The Science Behind Two Liter Bottle Rockets

2. It Ain’t Rocket Science…

3. Aerodynamics
The word comes from two Greek words: aerios, concerning the air, and dynamis, which means force
Aerodynamics is the study of forces and the resulting motion of objects through the air.

4. Center of Gravity Point where mass is evenly distributed
The balance point
Rocket would rotate
around center of gravity

5. Center of Pressure
Point where aerodynamic forces are equally distributed

6. Rocket Stability In a stable rocket, the Center of Gravity (CG)
should be closer to the nose than the Center
of Pressure (CP).

7. Rocket Stability
Ways to make Center of Gravity (CG) closer to the nose to increase stability
Make the rocket longer which moves the CG closer to nose.
Add weight to nose which moves CG closer to nose.

8. Rocket Stability
Ways to make Center of Pressure (CP) further from the nose to increase stability
Place the fins as far to the bottom of the bottle as possible.
Do NOT make the fins too large.
Select a fin shape that is larger at the bottom than the top (triangle).

9. Newton’s Laws of Motion

10. Newton’s 1st Law of Motion
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.

11. Newton’s 1st Law of Motion
How does this law apply to rockets?

12. Newton’s 2nd Law of Motion
Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).

13. Newton’s 2nd Law of Motion
How does this law apply to rockets?
The heavier the rocket, the more force must be
applied to get the same acceleration.

14. Newton’s 3rd Law of Motion
For every action there is an equal and opposite reaction.

15. Newton’s 3rd Law of Motion
How does this law apply to rockets?
As the water and air shoot out of the bottom
of the bottle (action), the rocket is thrust
Upward (reaction).

16. Forces Acting on a Rocket
A rocket undergoes several
forces during flight

17. Gravity A natural phenomenon where objects of mass attract each other
Gravity gives weight to physical objects and causes them to fall toward the ground when dropped.

18. Drag Sometimes called air resistance A type of friction
Forces acting opposite the relative motion of any object

19. Thrust
Thrust is a reaction force quantitatively by Newton’s 2nd and 3rd Laws of Motion
When something expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction on the mass which is the force called thrust

20. Rocket Launch