0.00736
=1.20 m/s
NOTE: The data logger was set as ‘timing’ and then ‘timing at A’ mode
After completing my preliminary experiments, I thought that the most promising ling of investigation was Preliminary Experiment 2, because the Data Logger gives an advantage, which removes the disadvantage of Human Reaction time. makes it more likely for my results to be more accurate. So the question I investigation is, Is there a relationship between Velocity (V) and Height (H).
To investigate this I used the following equipment:
Ramp- To roll the trolley off of, vary the height of the surface.
Two light gates- To pick up the readings from point A to B
Data Logger- Connected to the two light gates, to show readings
Metre Ruler- To measure the height on the slope/ramp
Standing Clamps-To holding the two light gates and slope in place.
Interrupt Card
To make sure I got accurate and reliable readings I used a Data Logger to record the time, because it times to the nearest 100th of a milliseconds. I also used a light gate so there was no possibility of human error.
Collecting Data
To insure that my investigation was a fair test, I tried to position the trolley at the same starting point for each drop/release. I made sure the trolley was completely stationary at the start. For my safety I made sure there was something steady at the end of the ramp, so the trolley did not roll off and injure someone.
My preliminary experiment number 2, showed me that starting with a ramp of 10cm in height and going up in 5cm to 30cm, would be reasonable for my investigation. It also showed me that keeping the length of the starting point on the ramp the same was a reasonable decision.
I noticed that I struggled to read the metre ruler accurately unless my head was in level with the direction (vertically) that it was in. To overcome this I had to make sure that I twisted my head to read the measurements and had another person holding the metre ruler steadily.
The following are the results I have accumulated from carrying out my experiment (Preliminary Experiment 2). This data will help me to conclude and evaluate.
Interpreting Data
In Graph 1, there was a curved line of best fit with only one outlier, showing that the higher the height of the ramp, the higher the final average speeds. For Graph 2, I expected to see a straight line of best fit going through the Y Axis (0, 0), but this is not what occurred.
For my results, I cannot say that V₂ is proportional to H. I expected to see that V₂ was proportional to H because: KE =GPE
1/2mv₂ =mgh
1/2v₂=gh
v₂=2gh
Evaluation
Throughout the method, the problems I faced were that the timings I got were largely scattered which is not what I expected. This may have been because it was difficult to position the trolley right next to top of the Light Gate without starting the timer (Interrupt Card).
To improve the method in future, it may work better to mark the start point for the trolley, so I know where to position it each time.
Assessing my results, I am confident that Graph 1 is accurate and reliable, because it shows a smooth curve of best fit, which is what I was aiming to see. However, I am aware that Graph 2, is not reliable as it did not show a straight line of best fit.
