Water Rocket Analysis
Name:
Period:
AP Physics
Scoring
/20 pts
/20 pts
/15 pts
/20 pts
/75 pts
Completing Your Rocket
Rocket Launches
Height Attained
Rocket Calculations
Total
Data
Rocket Mass (mR) =
kg
Water Mass (mW) =
Total Time from Launch to Landing (ttotal) =
Angles –
Height (h)
A:
B:
kg
s
C:
D:
m
Theoretical Predictions. According to theory, predict what your rocket should do if it launches straight
up. For our predictions, we will simplify what is happening in the rocket and ignore messy realities such
as air resistance. At the end, we can compare with your actual, measured height and think about how
good our simplified model is.
1. How much energy did the rocket have when it was at the highest point in its flight? [What type of
energy is it?]
2. If we assume that the rocket reached burnout – the point where it has exhausted all of its fuel and
reached its maximum velocity – when it was 1/3 of its final height off the ground, how fast was it going
at burnout? [What kind of energy will tell you about its velocity? How much of it is there?]
3. a) How does the rocket acquire its upward momentum if it starts out at rest?
b) How fast must the water leaving the rocket travel downward (before it starts free-falling) in order to
conserve momentum? [We will be finding an average value – it may be different for the water that
leaves at different times.]
4. a) How quickly is the rocket accelerating while it is going upward in order to reach the burnout point
at the right speed?
b) How strong is the average thrust from the rocket to accelerate it that quickly? [What forces go into
the net force while it rises? How do you know how big the net forces is?]
c) How strong is the average thrust on the water while the rocket is rising toward the burnout point?
Explain.
5. a) How long does it take the rocket to rise to the burnout point if it is accelerating at a constant rate
to that point?
b) How long does the rocket take to go from the burnout point up to its apex? [What state is it in after
the rockets stop? What forces act on it? How do they affect its motion?]
c) How long does the rocket take to fall from the apex back to the ground?
d) What is the total time for the rocket’s flight?
e) What is the percent error between our measured total time and our calculated total time? Why do
you think they are different?
Reflection:
Write a short reflection on your rocket and its performance. Your reflection should cover the
following ideas (each makes a wonderful paragraph): 1) Describe how your rocket was designed (give
the materials and sizes of the different pieces of the rocket); 2) Explain why you chose to make your
rocket the way you did. What was the incentive to use particular materials or particular size pieces?;
3) How well did your rocket perform? Were you satisfied or disappointed?; 4) What would you
improve about your rocket if you were to make another one? List specific improvements you would
make to enhance your rocket’s performance. (No improvements is not an acceptable option. Even the
best rocket can be made better.)