Things That Fly
Part 1:
Foam Rocket Launch
Materials
Rocket:
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Rubber bands (#64)
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30 cm of 1/2'' Foam Pipe Insulation
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9 x 9 cm Cardstock Square
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3 8'' Zip Ties
Protractor/Launch Device:
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Meter stick
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Binder clip
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String
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Washer
Especially when working with children, remember your safety goggles!
Here's a picture of my group launching our rocket at an angle of 20°.
Rocket Launch Data
This is a data chart that contains the angles at which the rocket was launched and the corresponding distances that the rocket traveled at those angles. We held three trials and took the averages of those trials in the last column. If you look at the averages on the data table, you'll notice that they start on the higher end and show a downward trend. This means that as the angle increases, our data shows that the distance decreases. This means that the data shows a negative correlation. You can see this visually on the XY graph below.
In the XY graph to the right, the data from the table above is reflected. The data on the x axis is the angle at which the rocket was launched (what you manipulate or control) and the data in the y axis is the distance in which the rocket traveled (the outcome or response to your manipulation). The line on the graph illustrates the relationship between the two.
Follow these steps to create your own XY graph:
1. Open the Create A Graph website and click the XY option.
2. Select the XY type that you would like to use. The option are line, bubble or scatter plot. The graph to the left is a line graph.
3. If desired, select your preferred style.
4. Next give your graph a title (I named mine Foam Rocket Distance) and label your X (Angle at Launch) and Y (Distance) axes.
5. You can style your line width, point size and color if desired.
6. Enter your data in the x and y tables.
7. If you want, you can enter an x and y min and max. This will mark the points at which your graph starts and ends.
8.If you click on the labels tab, you can personalize your title and x and y labels.
9. Now you can click on the preview tab to make sure your graph is to your liking.
10. Lastly, your graph is ready to print/save.
This graph was created using a kid-friendly program called Create A Graph.
The Science Behind the Rocket
Where does the energy that makes the rocket fly come from?
Energy Transfer Process
All life on the earth depends on a cycle called energy transfer to live. In this diagram, the plant is receiving energy from from the sun and converting that energy into glucose (a process called photosynthesis). The glucose gives the plant the energy it needs to grow and produce apples. The apple is then eaten by me and converted into potential energy that gives my body the potential ability to move. Next, I pull the string on the rocket- extending the rubber band and giving the rocket gravitational potential energy. Gravitational potential energy is the capacity that an object has to do work with the force of gravity working on it. When the rocket becomes airborne, the gravitational potential energy turns into kinetic energy- the energy that an object possesses when it is in motion. The rocket then travels through the air in the path of an arc and lands.
Why does the rocket move in an arc?
When airborne, kinetic energy gives the rocket its momentum to move forward. The rocket uses the kinetic energy from the snap of the rubber band to move as high as it can until its motion is acted upon by gravity. As it moves, it is being acted on by the air resistance (pushing against it and slowing it down) and the force of gravity (pulling it toward the ground). These unbalanced forces end up being stronger than the kinetic energy which is why the rocket ends up being pulled to the ground. The rocket would continue to travel in a straight line for infinity if it was not acted on by gravity.
What's the difference between this method of propulsion and the propulsion used in a rocket ship?
The foam rocket receives its push from the snap of the rubber band. This is a good demonstration of Newton's Third Law of Motion- every action has an equal and opposite reaction. The force produced by the rubber band causes an equal and opposite reaction in the foam rocket causing it to take flight. A rocket ship uses continuous acceleration provided by fuel to resist the forces of gravity and air resistance until it breaks the atmosphere. The force of propulsion is much greater than the force of gravity and air resistance.
Above is another example of Newton's Third Law demonstrated by a balloon. As the air moves out of the balloon, the balloon is propelled forward.
In the video to the left, Jeff is kneeling on a rolling pallet and holding a weighted exercise ball. As he throws the ball forward, he is thrust backward. The action of him throwing the ball causes a reaction moving him backward. The ball has a lot of mass and the wheels do not have enough friction to stop Jeff from moving. After this demonstration, Jeff threw the ball standing. He did not move because the friction between the floor and his shoes was greater than the force of the ball.