- I will place the tub in front of the band. At first, it will have no weights inside, the weights will be increased by 100 g each time the tub is fired. We decided on a range of 100g to 900g because I thought that this would be enough to be able to analyse different stages within the test.
- I will place the ruler alongside the stool and our surface.
- My partner will sit on the stool, and I will pull back the tub and band to the marked place, and then I will let go.
- I will then measure the distance it went.
- I will then add 100g to the tub and repeat the previous steps.
- I will repeat the whole experiment three times to ensure that my results are accurate.
Fair Test:
I am making this a fair test by keeping everything the same apart from the mass. It is important to do this because my results will be affected if anything changes. I will keep the surface the same because different surfaces will cause varying amounts of friction. The elastic band has to stay the same because the different bands will have different amounts of energy. The person pulling back the band will stay the same because the amount of strength, energy, and technique will differ depending on the person. How far the band is pulled back will also stay the same because the force will differ depending on how far it is pulled.
Results Table: showing how far a margarine tub goes depending on the Mass.
Analysis:
My graph shows that the higher the amount of Mass, the shorter the distance the tub travels. The more the Mass is increased the more friction occurs. The more friction there is, the less time and distance it takes for the kinetic energy to transfer into heat energy.
My prediction was partly right, when the 100g Mass was in the tub it went about 180cm, when it was 200g it went 120cm, so in the first stage of the experiment the distance did not half when the weight was doubled. However, when the 400g Mass was in the tub it went about 80cm, when the 800g Mass was in the tub it went about 40cm, so the distance did half.
Evaluation:
My experiment showed me how weight affects how far a margarine tub travels when fired. My experiment proved to be quite fair because most things were kept the same. One thing that was hard to keep the same was how the tub was fired, it proved impossible to keep the pulling back technique exactly the same. I feel this may have affected my results.
I measured the distances quite accurately, I always measured from the back of the tub and measured to the nearest cm. There is always room to be more accurate, I could have measured to the nearest half cm and so on. I think my results were fairly reliable because almost everything was kept the same, if I repeated the experiment I think I would get similar results.
When the 100g Mass had been fired in the tub, on one occasion it went 195cm and when the same was done with the 200g mass the distance shot down to 120cm. I was surprised by the gap in distance, because as you go further into the experiment the results get much closer together. Although I did get some unexpected results I think the experiment went well because it was fair and accurate.
