Things That Fly: The Rocket!!
The Project:
In this experiment, we constructed foam rockets, to test what was the ideal angle for the farthest distance of the rocket. This would test for angle measurements and bring in understanding to concepts such as measurement and force.
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Here is a link to the site that gives instruction to making of these rockets.
Materials:
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1/2 pipe insulation (about 30 cm)
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zip-
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ties (3)
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heavy duty string (about 100 cm)
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rubber band
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cardboard/poster board
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make into a 9 cm square​
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Directions:
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Tie the string ends together to make a loop
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Knot together the string and the rubber band so they make two separate loops
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Zip-tie them together so each loop is on a different end of the zip-tie
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Place this new strand inside the 30 cm pipe so that the rubber band is sticking out from the top and the string is hanging out from the bottom.
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Zip-tie the top of the rocket so that the strand's zip-tie is below this new zip-tie. This should allow the rubber band to pull but not slide in and out of the rocket.
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Cut a 9 cm square out of poster board
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Cut the square into two triangles
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Cut a slit from the tip of the triangle to ha​lf way point on one triangle
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Cut a slit from the bottom/hypotenuse to the half way point of the second triangle
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Put one triangle into the other to make the wings of the rocket
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Cut 4 equidistant slits that are nine cm into the rocket to place the wings in the rocket.
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Slide the wings into the slits and place a zip-tie under the wings to keep them in place. Do not need to tighten fully to allow the string to move.
How to cut the Triangles:
How to set the angles:
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Clip the paper protractor to the meter stick
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Have a weight on a string and clip it on so that when the angle of the stick is at a 0 degree incline, the string is on the 0 degree line of the protractor...
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This will mean whatever angle you tilt the stick will be measured on the protractor!​
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The Rocket in Action!
The RESULTS...
rubber band
Zip-tie
Last Zip-tie
Wings placed in the slits
This link to "Create a Graph" is a great resource for students to use in making graphs online. They can choose from bar graphs to line graphs (or X Y graphs on this site). They input all the data such as the title of the graph and the titles of the X and Y axis. They can input the data and the site will produce a proportional graph!
The Science...
There are various concepts this experiment shows students....
Energy Transfer:
The movement of the rocket shows there is energy. Where does the energy go though? The actual propelling of the rocket is due to the stored energy from the rubber band. The rubber band was pulled to the 20 cm mark on our rulers to keep the distance equal. This pull gives the rubber band Elastic Potential Energy. Releasing the rubber band releases the stored energy allowing the rocket to launch in the air. The movement of the rocket is known as kinetic energy. The rocket eventually hits the ground, and when it does, the energy is transferred into the crash resulting in friction and sound.
The Arc:
The rocket does not move in a straight line up in the air, but but moves in an arc. This can be explored by students. Once the rocket is in motion it will tend to want to stay in motion due to inertia.
However gravity is a pretty powerful force and it will eventually pull the rocket down to the ground. That is why it makes an arc. Gravity acts as an unbalanced force to the rocket's tendency to keep moving at the angle it was propelled.
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So why the DIFFERENT ANGLES??
As is seen by the graph of the distance our rocket traveled, some angles lend themselves well to the rocket traveling a longer distance. If the angle is too large, such as 60 to 90 degrees, then the rocket is spending time moving in that same angle once it leaves the meter stick due to inertia. It goes higher, but not farther. Once gravity begins to pull the rocket down, there is some more distance covered. So if you start with the rocket at a smaller angle, it will keep moving at that angle covering more distance versus height.While it will reach the ground faster since it does not have much height, being propelled at a closer angle to that of a straight line allows it to cover more distance than height while it is in the air.
Difference from real rocket ship:
While the propulsion for this rocket is due to the energy from the rubber band, this is different from the propulsion that one would see from a real rocket that would fly into outer space. As is seen in the rocket we created in class that is shown in the video above, the gases are heated up and expand and the rocket reacts by shooting upwards. This is similar to what happens with a real rocket. The gases are forced out of the exhaust (the action) and the reaction is to propel the rocket in the opposite direction. This is known as Newton's third law. This states that any action has an equal or opposite reaction. The gases are pushing one way, while the response of the rocket is to move in the opposite direction. However the foam rockets we created were propelled due to the inertia from the rubber band. This is different from a real rocket.
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This can be noted from the experiment viewed in class as well (represented by the picture). A balloon was blown up and taped to a straw that was run through a string hanging between the walls of the classroom. We predicted which direction the balloon would travel across the string when the air was let out of the balloon. As the air was pushing out of the balloon, the balloon has the opposite reaction. The air is pushing out of the balloon towards one wall while the balloon does not follow the direction of the air. It moves towards the other wall, thus showing Newton's Third law. This is different than how our foam rockets were propelled. Inertia has objects continuing to move in the same direction as the force. This law has two things acting and reacting against each other.
Here is the data table showing the different angles and the average distance the rockets traveled when propelled at that angle.