Apparatus:
- A standard stool
- A margarine box and lid
- A Newton meter
- Between 50g and 100g of sand
- Electronic scales to measure sand
- A metre stick
- A durable elastic band
Method: Firstly, I will measure the amount of sand I will need to perform the first weight. I would start with the lowest mass first to save getting my hands dirty. I will make sure that it is distributed consistently throughout the margarine box, otherwise it might turn upwards if the force is aimed at the lighter end. Also, I will make sure that the weight does include the lid, as it counts as part of the lid, and it also conveniently keeps all of the sand nicely in the box.
After that, I will place the box with the lid just in front of the elastic band. Then using the Newton metre, I will measure the force that I am going to apply. I am going to use a 10N force, as it is the most force it will take, and it is more likely to be able to launch the box further at the higher weights. I must remember that it is a constant force because I said in my prediction that I was only going to have one variable in this experiment. Two variables will just complicate the experiment and make it hard to find patterns in my results. I shall prise the Newton metre away, but catch the elastic band in my fingers, still keeping it at 10N. I shall slide the margarine box into the middle of the elastic band, as more kinetic energy is stored there, and without pulling it back, release the elastic band. When the box has come to a complete stop, I will measure from the box’s back point, as this is how far the box has travelled. I will record this result on a table, and to ensure credibility, I will repeat that experiment once more to catch out any ‘rogue’ results.
The weights of the box in the experiment will be: 50g, 60g, 70g, 80g, 90g and 100g. I chose these weights because I found out that weights below 50g flew too far and the metre stick wasn’t long enough. I also found out that weights above 100g were too heavy and travelled little or no distance. The gap between each weight is 10g because it is a consistent pattern.
Fair Test: A fair test must be ensured at all times in any experiment to keep results as accurate as possible so that appropriate conclusions can be drawn. The main way I hope achieve this is by repeating this experiment a further one more time so that an average can be taken and anomalous results can be spotted before they are taken as genuine ones.
As well as this, I must consider the apparatus I am using. Different equipment has different measurements, properties and configurations. Take the margarine box for instance. One could be more aero dynamical, the other no aerodynamical. The less aerodynamical it is, the more drag it has, the slower it is and my results won’t be as accurate. If I switch between the aerodynamical box and the not-so aerodynamical box, I will lose credibility on my results and I will not be able to draw relevant conclusions. Should my experiment be spread out over different days, I will mark all of the equipment I used on the first day and make sure I find it on the next day of collecting results. I will also make sure that I am working with the same people as different people have different opinions, different techniques and different views. I need the experiment to be as consistent as possible, so I will have the same people working with me.
Another is that the set-up must be the same for both experiments. If this doesn’t happen then I would not expect very accurate results. As well as this, I must consider how accurate I want my results to be. I’ll give my results as two decimal places as you cannot go higher than 99cm before turning to a new metre.
Results:
Conclusion: From my graph, you see that the line of best fit does go downward, although the results are a little inaccurate. The fact that the line of best fit does slope downward could prove that my hypothesis is correct. I think that my first two averages contained anomalous results, as the two results in each weight were very inconsistent. If I had more time, I feel that to improve the graph, I should re-test these results and configure the graph to those conclusions. However, I still believe that my prediction was correct. Although my results were a bit scattered across the graph, most of the points are still very near to the line of best fit, indicating a pattern. I hypothesised that when you left the force the same, you had to increase or decrease the mass to obtain a variable. When you changed the mass, it is directly proportional to the change in acceleration. For instance, if you increase the mass, it will decrease the acceleration. I also predicted correctly the shape of the graph as being as a downward curve, because as one point is increasing (mass), the other point (distance) is decreasing.
Evaluation: I felt that the experiment procedure could be greatly improved to obtain much more reliable and credible results. Even though I did repeat the results for each and every weight, I feel that anomalous affected the average length too much. Since each weight only takes a short minute to perform, I think that I could repeat each weight twice to get three results, or even four times to get five results. This amount of results should iron out the anomalous ones so that they don’t affect the average length, and it will lead to credible results and a nice line of best fit.
For my experiment in particular, I would have most definitely chosen a different surface to perform it on. The particular workspace I chose was by a doorway, which most probably contained debris from the outside world. I think that I should have at least swept the floor using it as a work area to remove the debris. It was also a tiled floor, which meant that the margarine box was sometimes slowed down by the cement gaps between the tiles. If I did the experiment again, I would definitely choose a workbench as they are smooth and have no obstructions in them.
I believe that the elastic band had an affect on the experiment as the more times I pulled it back, the band kept stretching and stretching, and I didn’t have the same power for the fourth weight as I did the first. To counter this, I would either choose a more durable elastic band, or swap the elastic band after each weight, so it will remain in its peak condition. However, I will make sure that each band I use has the same properties, like it’s thickness, and it’s level of durability.
Measuring the distance for each weight was quite an unreliable task. I used a metre stick, and without any guidelines, I had to roughly estimate where the back of the margarine box was. This was a very unreliable method. To counter this if I were to do improve this procedure, I would draw guidelines, using washable ink, every each half centimetre. The fact that the results were rough estimates meant that they weren’t very credible compared to results that were measured accurately.
To sum up, I don’t think that my experiment was very reliable, if anything, it was flawed. I think that next time, I should read the fair test steps and follow them more closely, and use the above corrections. However, there was a subtle downward curve that required disposing results, but ultimately, the procedure can be greatly improved. My conclusion couldn’t be that strong either and my hypothesis wasn’t proved, as there wasn’t enough evidence to do so.
