4. Discusion


Key Findings
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Figure 33- Speed-Weight Graph


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Figure 34- Average Acceleration-Weight graph


From Figures D to K - Distance-Time Graph, we can conclude that as the number of weights increase, the average speed will decrease.


From Figures L to T - Velocity-Time Graph, we can conclude that as the number of weights increase, the average velocity will decrease.


From Figures D to K - Acceleration-Time Graph, we can conclude that as the number of weights increase, the average acceleration will decrease.


Explanation of key findings
From figures D to K - Distance-Time Graph, we can observe the gradient of the lines decrease, thus, we can conclude that the average speed decreases as the amount of weights in the car increase. Since the car’s average speed is faster, the gradient of the graph will be steeper.


From the best-fit line in figures L to T - Velocity-Time Graph, we can observe the height of the lines decrease, thus, we can conclude that the average velocity decreases as the amount of weights in the car increase. Since the car’s average velocity is faster, the gradient of the graph will be higher.


From the best-fit line in figures U to AB - Acceleration-Time Graph


Evaluation of hypothesis
Contrary to our hypothesis, the speed did not remain constant after the car reached terminal velocity. Instead,it decelerated then accelerated again, repeating this cycle again and again. Thus, we can infer that the car probably went on short burst of speed, instead of remaining at a constant. A possible reason might be that the car moves forward only when the bluetooth signal is received. Thus whenever the signal stops the car would slow, and whenever the signal is emitted the car would speed up again.
Despite of this, the best fit curve still shows the car remain roughly constant so our hypothesis is still partially correct.


Areas of improvement

  1. A proper camera, instead of a macbook, could be used for filming the car as the video filmed by the car was very pixelated so the car could not be tracked more accurately.
  2. A LED light bulb could be place at the front tip of the car for easier tracking since it is very hard to point the exact point of the car every time when pointing the mass on tracker.
  3. The conversion of the hydrogen to electricity should be more reliable as there are times during our experiment where the car burns through its electricity very quickly.
  4. A track could be made to ensure that the car would move 100% straight.

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