Making sense of data - Stopping distances
Extracts from this document...
Introduction
James Fung 14thMarch,2002
Physics coursework --- making sense of data
Stopping distances
Introduction:
In this coursework, I didn’t carry out the experiment because we are meant to use the results provided from the teacher to do an analysis. And my coursework is about the stopping distance of a small ball bearing on a carpet after rolling down from a runway with various distances. First, the ball was placed at 100mm up slope and allowed to fall. When it reached the carpet, the carpet caused deceleration to the ball, so after a certain distance, it stopped. Then, the procedure was repeated for 3 times to get an average result of the stopping distance. Next the ball was placed at 200mm, 300mm . . . 800
Middle
Distance up slope (d) /mm
Stopping distance 1 /mm
Stopping distance 2 /mm
Stopping distance 3 /mm
Average stopping distance (s) /mm
100
154
154
155
154.3
200
342
344
344
343.3
300
464
472
464
466.7
400
563
572
573
569.3
500
667
687
690
681.3
600
817
830
835
827.3
700
930
940
940
936.7
800
1100
1095
1100
1098.3
Using simple geometry, I can work out the corresponding height of a particular distance up slope. 860mm
172mm d
e.g. When d = 800mm
= 
h = 160mm
Distance up slope (d) /mm | Corresponding height (h) /mm | Average stopping distance (s) /mm |
100 | 20 | 154.3 |
200 | 40 | 343.3 |
300 | 60 | 466.7 |
400 | 80 | 569.3 |
500 | 100 | 681.3 |
600 | 120 | 827.3 |
700 | 140 | 936.7 |
800 | 160 | 1098.3 |
Kinetic energy = 
mv2 (where m is the mass in kg, v is the velocity in ms-1)
Potential energy = mgh (where
Conclusion
- the meter ruler --- the limit of accuracy was =
0.5mm, this is due to the distance apart from each unit of the meter ruler is 1mm and as the data of the stopping distance given, all decimal places have been rounded up - the air resistance --- although the air resistance that acts on the ball when it decelerated on the carpet would be small, it could still have an effect on the rolling ball. However, I have ignored it throughout all my calculation and analysis, so this could have made it inaccurate.
- assumption --- during the analysis, I have made two assumption, which is the energy wasn’t lost, all potential energy was converted into kinetic energy, and the deceleration in each case is constant until the ball stopped. This again has affected the result as things are not likely to be as assumed in real life.
- friction --- throughout the analysis, I haven’t mentioned about friction at all. As friction is proportional to force, so without taking this into account definitely lead to inaccuracy.
END
This student written piece of work is one of many that can be found in our GCSE Forces and Motion section.
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