Using these heights will mean that a good range of results will be obtained, therefore making this experiment more reliable and easier to draw conclusions from.
Preliminary Work
During my preliminary work I tested the lowest and highest heights from which I , I did this to find the shortest and longest times it would take to do the experiment. The results obtained are shown below:
These results have confirmed that I will use the heights shown in the table above.
Reliable Test
The method I will use to make sure that my results are reliable is to test each height three times. This will then give me three results for each height, after this I will calculate my average or mean time. The average will give me a good overall reliable result for my experiment.
Fair Testing
The ways in which I will make sure that my experiment is conducted in a fair and affective way are as follows:
- Start timing each experiment when the car is released and stop when the car has reached the end of the ramp.
- Use the same apparatus for each experiment, which means I shall use the same car and ramp so that the experiment is done in the same conditions. I shall use the same car and ramp because then there would not be a different mass or shape of the car, or, there would not be a different type of friction on the ramp as both these affect the kinetic energy.
Predictions
From my preliminary work and my studies on this topic I can make predictions on what the results in the assessed practical will be.
I predict that as the height used doubles the kinetic energy of the car will also double. This is because as you double the height you double the Potential Energy therefore you double the kinetic energy, as the Potential Energy at the start is the same as the kinetic energy at the end. On the other hand if I decrease the height there will be less potential energy with the car, this means the car will be slower so there will be less kinetic energy. I think that the height from which the car is released and the kinetic energy will be directly proportional to each other, because height increases the kinetic energy will also increase. I should find that the highest height used (50cm) is five times faster than the lowest height used (10cm).
