The same textbooks must be used each time because different ones might change the height of the ramp slightly, which will make the experiment unfair and the results unreliable.
Method:
- The apparatus is set-up as shown, which will mean that the rate of velocity can be calculated once the trolley has been let go. It will travel down the ramp and I shall record the time it took the trolley to reach the end with a stopwatch
- The height of the textbooks will then be measured, so that the height of the ramp is known, once placed on them.
- The trolley will then be held at the top of the ramp, where it will gain potential energy. I will be ready with my stopwatch for when my partner lets the trolley go.
- The trolley is then let go. The potential energy will then transfer into kinetic energy and increase in speed.
- Once the trolley has travelled the distance, I will have the results recorded from my stopwatch.
- This will be repeated three times, so that an average can be taken and to check that the results were correct.
- The height of the ramp will then be made higher, and the experiment will be completed once again. This will be done three times as well.
- There will be five different heights to test out altogether. These heights are 3cm, 8cm, 13cm, 18cm, and 23cm.
Results:
Analysis: During this experiment, I found out that as the height of the ramp increases, the rate of velocity also increases. This proves that the prediction made earlier is correct because as the ramp increases in height, there was more potential energy acting on the trolley and less friction, so when the trolley was let go it went faster than when the ramp was lower because there was more potential energy to transfer into kinetic energy.
I also found out that by using the formula V= √2gh, I could find out what the real velocity rate would be in a perfect world with no friction, wonky wheels, etc… For the first height, my average result was 0.512m/s and using the formula showed it to be 0.767m/s. This shows that there is 0.255m/s difference. This must mean that there is quite a bit of friction slowing it down. For the second height my average result was 0.716m/s, the formula shows it to be 1.25m/s. This one shows that there is 0.534m/s difference. The last result I got for the tallest height was 1.115m/s and the formula shows it to actually be 2.12m/s. This shows that there is a 1.005m/s difference. As the height increases, I have found that the actual velocity rate also increases more each time, but at a less amount than the last time. It also shows that as the height increases, my results become more unreliable as it progresses. My results do prove though that there must be more potential energy when the height of the ramp is higher, so that the potential energy can transfer into kinetic energy, making the trolley's speed faster than when the ramp is at a lower height because there isn't as much potential energy to transfer into kinetic energy. The graph also shows that as the height of the ramp keeps getting higher, the velocity rate gradually starts to level off, so once it has completely levelled off it means that the trolley can go no faster however higher the ramp gets, meaning that it has reached terminal velocity
Evaluation: The results obtained are fairly accurate although the bottom half of the ramp was not measured for its height, so I had to guess a reasonable height that it could be and then take that away from the height of the ramp at the top, where it rested on textbooks. This could mean that if the guessed height is not completely accurate, then the results will not be as accurate as they could have been if I had measured it when I first carried out the experiment. There are no anomalous results to be accounted for either. The method used to carry out the experiment was simple and easy, and I feel that since I did each stage three times my results from the stopwatch were accurate.
Improvements which could be made to improve the reliability of the evidence and the way in which the experiment is done, could be to make sure that the actual height of the ramp is known, to make sure that the ramp used has no bumps or chips in it because this could affect the speed of the trolley and to make sure that the trolley has no wonky wheels which could also affect how the trolley moves.
The evidence collected is quite reliable to support a firm conclusion because it still shows how the velocity rate can change according to different heights of the ramp, but I would suggest that the experiment to be tested again just so that the proper height of the ramp can be known for the velocity rates recorded down and to check whether or not the results collected before are accurate.
Further which can be done, could be to see how gravity affects the velocity rate of a trolley or to see how variations in mass of the trolley can affect the velocity rates.
