Physical Science Institute
Summer 2013
3-2-1- Blast Off
PRE-LAB
In this activity the launch velocity of a rocket using the Law of Conservation of Energy will be determined. Is has been previously observed that an objects energy can transform from one form to another. An air powered rocket will leave the ground with kinetic energy that will transform into potential energy as it reaches higher and higher altitudes.
With a full understanding of the Law of conservation of energy, the height and initial velocity can be determined from ground level data observations.
Begin by predicting a graph of the position, velocity, and acceleration versus time graph for the flight of a rocket launched vertically upward on the graphs below.
On the position versus time graph, label the points where the rocket has the highest potential energy, and also the highest kinetic energy.
Velocity vs. Time Acceleration vs. time Position vs. Time
0 0 time time time
Arbor Air Powered Rocket
Trundle Wheel
High powered cap
Stop watch
MATERIALS
Altimeter
Three angle wedges super cap
Bicycle pump
PROCEDURE
1.
Safely install the cap onto the rocket stand as instructed.
2.
Insert the rocket over the launch tube and secure it to the cap.
3.
Have a member of the team prepared to record the time of the flight of the rocket.
4.
When everyone is behind the safety line, begin pumping the bicycle pump. The rocket will launch when the pressure exceeds the capacity of the cap.
5.
Observe the angle at the HIGHEST point in the flight and record in the data table. Record the flight time in the data table.
6.
Measure the range the rocket flew using the trundle wheel and record in the data table.
7.
Repeat the launch sequence so that three angles for each cap have been recorded.
1

CAP
SIZE
LAUNCH
ANGLE
FLIGHT
TIME (S)
Physical Science Institute
Summer 2013
RANGE
(IN METERS)
ANGLE
WITH
ALTIMETER
CALCULATIONS & RESULTS
1. Draw free body diagrams of the rocket showing any and all forces acting on the rocket during the following points of the launch. (Use F t
to represent the rocket thrust)
2. Graphically determine the maximum height of the three super cap launches that the rocket achieved. Fill in the calculated heights in the table below.
Launch Angle
2

Physical Science Institute
Summer 2013
3

Physical Science Institute
Summer 2013
4

Physical Science Institute
Summer 2013
5

Physical Science Institute
Summer 2013
3. Use the time data and Range data to calculate the velocity of the three super cap launches for the Rocket has at the highest point. This is possible because the velocity can be calculated using the fact that v = d/t. Record this in the chart below.
Launch Angle
Velocity at highest point
4. Calculate the potential energy and the kinetic energy of the rocket at the highest point. Then determine the total mechanical energy.
Launch
Angle
G.P.E. K.E. M.E.
7. Use the Law of Conservation of Energy to determine the launch velocity of the rocket.
This is possible because the all of the Mechanical energy the rock has at the highest point, came from the kinectic energy at the launch:
M.E. = ½ mv 2
6

Physical Science Institute
Summer 2013
8. If the Rocket was to be shot directly upward, what would have been the height it could have reached?
Position vs. Time time
0
Velocity vs. Time time
0
Acceleration vs. time time
7