Courseworks

Physics Coursework

I aim to collect two sets of data in my physics coursework both will observe the stopping distances of toy cars travelling down a ramp. The first will be to see the affect of a change in mass on the car to the stopping distance. The second will observe the affects of the height of the ramp that that the car rolls down.HypothesisI predict that the mass of the car will not affect the stopping distance as doubling the mass doubles the stopping force which keeps the stopping distance the same.I predict that as the height of the ramp increases so to will the stopping distance increase. This will happen proportionally so if the height doubles the stopping distance will double.BackgroundFormulas:o s = 1/2mv�/F s=stopping distance m=mass v=velocity F=stopping forceo fs = mgh s=stopping distance m=mass g=gravitational field h=height f=stopping forceMethodI will use a clamp, a toy car, a tape measure, a one metre ruler, five 10g weights and some sellotape. In the first experiment I will keep the height of the ramp at 10cm so that height does not affect the stopping distance. Then the car will be placed at the top of the ramp and released, not pushed. The weight of the car will increase from 30g, the weight of the car, to 80g in 10g intervals. Six results will therefore be obtained and the car will be released from the top of the ramp three times on each weight to gain an average and hence fairer and more accurate results. I will then measure to from the ramp to the middle of the car. This will take place on the carpet.In the second experiment the weight of the car will be kept constant at 30g as this is the cars weight. The height that the car is released from will increase from 0cm to 25cm in 2.5cm intervals. Consequently, 10 results will be obtained and once more 3 results will be taken from each height to get more accurate results and I will measure from the end of the ramp to the middle of the car.PreliminaryIn my preliminary experiment I will do the experiment changing the height of the ramp. I will take three results from each height I will go up in 2.5cm gaps. I will do this on the bench.On BenchStopping Distance/cmAverage Stopping Distance/cm0,0,0024,26,2826105,104,109106Bench too short///////////////I discovered that the bench was to short as it did not provide enough of a stopping force and I will now do my real experiment on the carpet.ResultsOn CarpetHeight/cmStopping Distance/cmAverage Stopping Distance/cm00,0,002.510,9,78.7524,26,2625.37.538,41,3939.31069,69,7470.6712.598,102,10010015139,138,13712817.5144,143,146144.320151,156,150152.322.5162,173,17216925178,180,184180.67I checked my results for anomalies because I didn’t want any of my results to be false. I then circled in red the results which must have been a mistake. The only anomaly I could find was in the mass to stopping distance and as my three measurements taken where all strange, then I have concluded that it must have been maybe at the wrong height or wrong weight.GraphsAnalysisThe first set of results show the affect of mass on stopping distance. The results show that the mass of the car does not affect the stopping distance in any significant way. The results stay within 2cm of each other apart from the anomaly. The reason that the results remain similar is because of the equation s = mgh/F. The mass is (m), gravitational field is (g), breaking distance is (F), height is (h) and stopping distance is (s). When the mass doubles, the stopping force is then doubled, as they are proportionate, so the equation becomes 2s=(2m)gh/2F. This cancels out the increase in mass when it comes to the stopping distance so the equation remains s=mgh/F. My results show that I was correct in my hypothesis as the mass had no significant effect on the stopping distance. However my results were not at all perfect as there was some variation in the results.The second set of results show the affect of the height the car is dropped from on the stopping distance. They are proportionate as I predicted. The stopping height has a constant effect on the stopping distance because in the equation F =mgh. If the height is doubled the equation becomes F2s=mg2h. My results although quite accurate are not exact as the do vary a little. The perfect set of results would contain a straight line through the origin.EvaluationIf I were to do my experiment again there are a certain number of things that I would alter to help me to gain more accurate results. I would use low friction wheels on a rail which would limit the effect that friction has on my results. The surface I would use would be a no friction surface to limit friction so more. Another thing I would use would be a light gate because that would give me more accurate results. It would do this because when the toy car leaves the ramp it is slowed dramatically when its nose hit the floor. The light gates would allow me to measure the speed and using the equation s = 1/2mv�/F I could then prove my theory with more accuracy.A lot of energy was lost when the toy car hit the sides of the ramp so in future I could use a wider ramp to avoid this problem. As my car did not travel a straight line the whole way it would stop my results from being very accurate. I could cover the wheels in ink then using string I could measure the distance exactly however a lot more energy would be lost as the ink would create more friction. Also, by rounding my results up I lost some accuracy. Overall my experiment was not too inaccurate and I feel the results reflect the theory well.

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