To investigate the affect a changing slope has on the distance traveled by a toy car Essay Example

each of the possible independent variables, to find the one that suited the investigation best. I tested the weight, by attaching weights onto my chosen car with plasticine. The results were as follows:

Car released at height of 100mm

These results were not broad enough for a graph. This may be a good possibility for further experiments.

There were only two experiments possible for using friction as the independent variable; these were onto ramps laid out and onto a cutting of the easy clean carpet. The results were as follows:

Car released at height of 100mm

This experiment lacks potential as there are only two different tests you can do. Friction is also very difficult to measure unless as a calculated error.

At this point in the preliminary work, I decided to go from the slope directly to the desk as the desk would cause less friction as it was polished, as opposed to going from the slope to more ramps of the same material laid out flat. Having not been very satisfied with my results for the other two

possible independent variables, I stacked my hopes up that the height would be a good one to choose, and it was. I tested to establish a range of values to work within when it came to actually do the experiment. I wanted to limit myself to less than two meters from the bottom of the ramp for distance traveled. My results were as follows:

My range is to be from 30mm - 120mm. I am to test height.

Apparatus:

Ruler

Stand with clamp

Ramp

Desk

Toy car

Method: The ramp will be placed on the desk and attached to the stand via the clamp, the height will be taken from the starting line, 420mm up the ramp from the bottom, to the desk surface, and adjusted until the desired height is achieved. The car will be placed with the front of it on the starting line facing down the ramp. The car will be released and a measurement taken from where the car gets to, to the bottom of the ramp. Readings will be taken every 10mm height, between 30mm and 120mm; three readings for each interval unless an anomaly is spotted in which case a fourth test may take place. If the car goes off the side of the desk or collides with the wall running alongside the desk, the test will be void and have to be redone.

My experiment will be a fair test as the car will be the same throughout, keeping mass and axle friction constant, as will the desk surface and the ramp. Safety is not a key element in this experiment, accidents may be caused by carelessness and lack of attention, such as knocking the stand onto

one's toe, I will be extra-vigilant to avoid these.

From my preliminary work, I decided on the surface to be used and the independent and, subsequently, control variables. I also ascertained my range of values. A suitable degree of accuracy for measurements of the distance traveled is cm.

Results:

Heightof start (cm)

DT (cm) test 1    12;      11;       10;       9;         8;            7;           6;         5;        4;         3.

DT (cm) test 2   199;    175;    162;    144;      130;        112;       100;     70;      46;      27.

DT (cm) test 3    196;   176;    163;     141;     128;        109;       93;       67;      48;      27.

DT (cm) test 4    199;    176;    161;     138;     131;        113;        92;       71;      47;       28.

Anomalous result

I felt that due to the unfortunate crudeness of the equipment we were given to use, centimeters were as accurate as it was necessary to go. From my graph, you can see clearly that the trend is a straight line. It does not, however, go through the origin, without error it would.

There is one obvious anomaly, which could have been caused by any number of things, most likely it found a path down the ramp and along with the table that was smoother than the paths taken by the car during the other tests. This is shown on the

table and 'ringed' on the graph.

Analysis

The gap between the line of best-fit meeting the 'x's axis and the origin must therefore be an error due to friction of the wheels on the surface, and axle friction, besides drag which, I might add, would be negligible on a scale of this size. Another cause of the constant error was the fact that I could not find the car's center of gravity, and it would have been futile to try, so I started with the front of the car on the starting line instead of the center. The error seems to take up 1.4 units on the 'x's axis.

Two points on the line of best fit, are testing two for 5cm height and test two for 10cm height. We must subtract 1.4 from these results to reduce error leaving us with:

We can now prove proportion, excluding error, by doing the basic sum 8.6/163 and 3.6/67 leaving us with 0.0528 and 0.0537, these results being the scale factors are very similar in fact having just 0.0009 between them. This negligible error was probably created due to a very small inaccuracy in the plotting or simply the thickness of the line. I like to think the latter! My results have thus supported and/or proved my prediction.

Evaluation

My experiment was sufficient to prove my prediction but there was quite a large amount of constant error to be subtracted. I think that it was as good as it was

possible to make it with the equipment on offer. There are a tremendous amount of insignificant factors, which would produce a slight error in my experiment. Everything to do with friction produces an error, but the experiment was on stopping distance and, in a friction-free world, a car let go down a ramp, at any height, would have an infinite stopping distance. Introducing bearings into the car, or simply oiling could reduce axle friction. Excessive polishing could reduce desk friction; air resistance by doing the experiment in a vacuum and so on. A toy car complete with ball bearings on the axles could have been acquired but at the pointless expense. A polished desk would have helped reduce the error but it takes a lot more time to polish a desk than it does to subtract a bit of extra error. And a vacuum on the scale that we are talking about for my experiment would not have been possible as perfect vacuums are very difficult to achieve and the school can certainly not facilitate such a thing. My results contained one obvious anomaly it was higher than the other three readings for this height value. This would indicate a small accidental push on releasing the car. As it only happened once there was no need to devise a means for the car to be electronically released. I could further extend the experiment by changing the mass or measuring the acceleration of the car down the slope or the average speed.

Conclusion: This experiment was not very accurate, however, with a constant error having been established from the graph, the results became useful. There was no

need to refine the method further as I managed to prove my hypothesis and any other apparatus for reducing the constant error was not available to me. I conclude that, when friction is ignored, distance traveled is directly proportional to height.