# An investigation into factors that effect the braking distance of a trolley

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Introduction

An investigation into factors that effect the braking distance of a trolley. (1) Skill Area P: Planning Experimental Procedures Aim: To investigate factors, which determine the stopping distance of a trolley accelerating down a ramp. When a car is situated at the top of ramp, we say it has gravitational potential energy. When the car travels down the ramp, the gravitational potential energy is transferred to kinetic energy, so therefore KE= 1/2mv² (Kinetic Energy = 1/2 x mass x velocity²) At the bottom of the ramp work has to be done in order to stop the car; so therefore Work Done = Braking Force x Braking Distance Also, this must be equivalent to the original energy of the car, which was gravitational potential. So, assuming no other loss of energy: Potential Energy = Kinetic Energy = Work Done Background Information: When a mass is raised and there are no opposing forces acting upon it, the potential energy gained will be converted to kinetic energy as it falls back to earth due to the gravitational pull. The potential energy gained must therefore be equal to the kinetic energy it produces due to the theory of energy conservation - energy cannot be created or destroyed. This is shown in the formula: - PE = mgh From this formula we can assume that the height of the trolley will have a direct correlation to its stopping distance. It is logical to predict that if the height of the trolley (h) is increased the potential energy it gains will be larger and consequently the kinetic energy it is converted to will be greater. Therefore it is logical to predict that the greater the height of the trolley the greater the stopping distance will be. Because the kinetic energy will be greater as height increases so will the forces required to stop the motion and as the force used to stop the trolley is kept constant the stopping distance will increase.

Middle

The ranges of measurements I plan to use for the heights of the ramp are: * 05 cm * 10 cm * 15 cm * 20 cm * 25 cm * 30 cm * 35 cm * 40 cm * 45 cm The reason for this is because that they are reasonable heights to use. The numbers of measurements I will do are 3 for each height. This is a logical amount of measurements for the time of which the experiment has to take place within. Repetitions: The repetition of results is crucial to gain the best and most accurate results. The experiment will be repeated 3 times, for each of the heights, and an average will be taken, so that if any anomalous results occur then it will not affect the outcome as much as if only 2 recordings were taken for example. Apparatus: * 1 metre wooden runway * 9 ramps * Trolley * Marker pen * Metre stick Method: > 1. Set the height of the ramp (Ranging from 5 - 45 cm) > 2. Place the wooden runway on the appropriate ramp. > 3. Roll the trolley down the ramp 3 times for each height. > 4. Mark where the trolley stops > 5. Measure the distance form the end of the runway to the stopping point of the trolley to indicate stopping distance. > 6. Record the results produce a table and draw a graph to identify trends. Safety As with all experiments, safety is an important issue to make sure that nobody is hurt and nothing is damaged. * Basic lab rules will be followed at all times throughout the experiment such as not running. * The most important safety issue to note is that the runway should be stable so that it doesn't collapse and injure anybody or damage equipment. * Someone will ensure there is no possibility of the trolley going off in inappropriate directions.

Conclusion

Perhaps if I did the investigation again I would also see if mass affects braking distance. Accuracy of Results The results were measured very carefully and to the best of human judgement. I would estimate the results were measured to within the nearest centimetre. This is easily accurate enough to show a clear distance between heights, accurate enough that the repeated results didn't differ so much as a consequence of this correlation it proved my theory. Also, the graphs are fairly accurate due to the precision of the results, and you can see that there is a fairly accurate straight line. All in all, I am satisfied with the reliability of the results, as they have enabled me to analyse and do what I need with them. However, as with any experiment there are the occasional anomalous results, which I got, but this did not hinder any of my work, and can be explained. Strong evidence: My evidence was reliable and strong enough to support my conclusion, in graph this was clearly exploited. What Improvements Would Be Made If Redone? 1. Reduce the friction of the system. 2. Make the trolley more aerodynamic. 3. Electronically measure the stopping point for more accuracy with results. 4. Do the experiment more times. 5. I could use a real car but that would be very expensive and it would take a long time to get a lot of results, also biased results may occur. If we did any of these proposals I'm sure we would get a fairer test with more accurate results. Anomalous results: As far as I can tell, no anomalous results were present, (An anomalous result being a result that does not agree with the general trend of the other readings). Overview Overall, I think that the experiment was conducted systematically, and produced enough results with reasonable precision, which allowed me to show my prediction to be true. It correlated well with the theory and there were not too many unexpected results. ?? ?? ?? ?? 1 GCSE Science Coursework

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