# Margarine Tub

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Introduction

Investigate how the mass will affect the distance travelled by a weighted margarine tub when it is propelled along a runway by a stretched rubber band Planning A Hypothesis I predict that as the mass of the margarine tub increases, the distance travelled by the tub will decrease. I think this because as the mass increases the surface friction will also increases; this increased friction will cause the object to slow down and stop quicker and therefore in a shorter distance. The formula for kinetic energy is: Kinetic energy = mass x velocity squared. When any mass is propelled along a runway, it travels a certain distance. When the mass is heavier then travels a shorter distance, and when it is lighter it travels a longer distance because of the forces acting on it. It will also travel a longer distance because of the increased momentum. I expect that the graph will not be a straight line because of the velocity squared part of the formula; this will vary the gradient of the line of best fit. The gradient will change because you are not multiplying the velocity by a constant, but by itself so the larger the velocity, the more the number will increase by when squared. This is why the gradient is steeper at the start of the graph. ...read more.

Middle

I will measure from the same end of the tub when I pull back the elastic band and when I measure how far it has travelled. I will measure to the nearest centimetre because it is the most appropriate degree of accuracy, and I will measure across with another ruler to make the measurement readings more accurate. I am using a measurement sheet rather than a Newton metre to measure how far back I pull the elastic band, because the Newton metre only went up to 10 Newton's and this force didn't pull back the elastic band far enough to propel the projectile a suitable distance to measure. This would make it hard for me to collect an appropriate range of accurate results. I need to make sure I don't stretch the elastic band too much that I reach the elastic limit of the elastic band. If I do stretch the band beyond its elastic limit, as stated in Hooke's Law, the elastic band will behave inelastically so it won't return to its original shape. Data Collection Mass (g) Distance Travelled 1 (cm) Distance Travelled 2 (cm) Distance Travelled 3 (cm) Average (cm) 50 44.5 45 81 56.8 100 30.5 30.5 32 31 150 24 26 25 25 200 22.5 22 23 22.5 250 19 20.5 20.5 20 300 18 18.5 18.5 18.3 350 16 15.5 19 16.9 400 15 15.5 17 15.8 450 11.5 11 11.5 14.8 500 12.5 ...read more.

Conclusion

This is what I predicted would happen, and it was correct. I am pleased with my results and feel that they are as accurate as I could make them. I measured the distances to the nearest half centimetre because this was an appropriate degree of accuracy and made sure the ruler was in the correct position before taking each reading. If I did this experiment again, I would perhaps investigate more than one factor, and find out the effect they have on each other. For example I could investigate how far an object travels when propelled of an elastic band along an oiled or greased surface. Also I would investigate more weights so that my line of best fit is more accurate on my graph, I might also extend the range of weights to see if this made any difference. My percentage error was 14%, I worked this out using my expected table of values and my actual table of values, I used the formula Percentage error = (value - expected value / expected value) x 100. I had one anomaly whilst collecting my results, so there must have been a factor which affected this result when I was doing my experiment. This was probably a human error of misreading the length on the ruler; however it could have been any of the factors explained on the first page. Finally, I am pleased with my results and overall experiment and I feel I produced an accurate set of data. ?? ?? ?? ?? Ahmed Ismail Physics Coursework ...read more.

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