Task 15

Materials and tools for a working group:

PET bottle, pipe, nozzle, paper, scissors, glue, gauge from task 10

What pupils have found in Task 10 and also what they examined in Task 14 can be verified by performing Task 15. Investigation is aimed at relationship between angle of shooting object and how far the object can hit the ground. It is also possible to perform this task separately from Tasks 10 and 14, at which point the task is to create an inductive conclusion on the explored relationship between the shooting angle and the impact distance.

To carry out this activity, the teacher needs to construct a simple device to drive a paper rocket usingair flow (see Figure 15). Hitting the PET bottle, pushed air reaches the end of the pipe and shoots a paper rocket that we put on the end. If we want rockets to get further under the influence of moving air, it is advisable to place a nozzle on the end of the pipe, i. tapered hose profile that causes air to compress and thus accelerate its movement. However, the device also works without a nozzle. The teacher first presents the equipment to the pupils and explains how to use it. The first task for the pupils will be to create a paper rocket that will flow the furthest if they put it on the end of the pipe and shoot it out with air flow. In order to understand what is expected of them, the teacher can have a very simple paper rocket ready and demonstrate the functioning of the mechanism.

To consider different options, the teacher leads pupils to think whether it would be better to make a longer rocket, shorter one, whether it is suitable to make a side squadron, as we can see on a real rocket, whether a rocket needs to be balanced, should be heavier at the front or back and the like. Subsequently, pupils try to create paper rockets, with the teacher guiding them in that they need to be made so that they can be pushed onto the „starting device“ (nozzle or hose outlet). After preparing rocket prototypes, the teacher guides the pupils to try out the missiles. As in Task 13, they also have the option of modifying their prototypes to fly further by comparing their own prototypes with prototypes of other groups.

Subsequently, they select the rocket that flies the farthest and use it for further investigation. The teacher suggests to the pupils to find out how far the rocket will fly if we change the angle of the pipe. For this purpose, they use a simplified protractor (see Task 10). If the pupils were not familiar with the function of this device before, the teacher will ensure it first. They put the simplified gauge on the pipe and see what number the string shows. They adjust the pipe so that the string points to the number shown in the table. They shoot the same rocket several times from the set device and measure the distance to which it has reached. They gradually change the angle of the shooting pipe according to the values in the table and add the data obtained (measured distance of the rocket impact). The measured data are then attempted to mark the graph. The table determines the measurements only for some values on the protractor. It is the intention that pupils realize that it is not necessary to have a complete set of measurements to reach a conclusion. It is then possible to work with the created chart in terms of developing extrapolation capability. Thus, the students only record the values measured for the selected angles in the graph. Subsequently, they try to conclude on the basis of the graph.

In line with the findings of Tasks 10 and 14, pupils will see that the distance increases and then decreases. By extrapolation (by creating an approximate curve) it is thus possible to determine what is the optimum angle under which the rocket needs to be fired to ensure it reaches its farthest. It is also possible to deduce to what angle the nozzle needs to be set if we want the rocket to reach a certain target. By solving the first part of the task, in principle, pupils learn to calibrate a created tool on a particular rocket. With the same rocket then they can hit the target quite accurately using the measured calibration data.

As you can see, the scale on the simplified protractor is reversed. That is, if the pupil has a value of 9, then the protractor does not point perpendicularly to the ground surface, but shows a perpendicular direction to the gravitational force of the earth.