Light Gate
Floor space for trolley to run along
Ruler
Computer Simulation:- Computer
Science Investigation Software
It is very important that I understand the safety aspects involved with the experiment. I will have to make sure the equipment is sound and that neither myself nor anybody around me will get hurt whilst the experiment is being carried out.
I will carry out the experiment three times for the light gate, and another three times for the computer simulation. From these results I will find the average time for both methods. I will increase the compression of the spring by two centimeters each time, starting at two and going on to fourteen centimeters.
Prediction
I predict that, as the amount of compression in the spring increases, so will the velocity of the trolley. I believe this as when the compression of the spring is increased, then so is the amount of stored energy in the spring (potential energy). When the spring is then released the stored energy will be transferred into the trolley, and this will cause the trolley to be pushed along. The energy that is transferred into the trolley is kinetic. This is what causes the trolley to move. So the velocity of the trolley as it passes through the gate, depends on the kinetic energy which is transferred into it. I think that as the compression of the spring is increased, so will the velocity of the trolley. I feel that this will be the case for both the simulation and light gate methods. However, I feel that the simulation method will end up with faster times as it does not have to take things such as the smoothness of the surface that the trolley runs on, nor the friction created.
Here are the formulas that I have used in my coursework:
Velocity (Metres Per Second) = Length of Card
Average Time
The length of my card was 10cm therefore my formula is 0.1
Average Time
The formula I will use to find the kinetic energy transferred from the spring to the trolley is: -
KE = 0.5 x mass x velocity²
KE = ½ mv²
The mass of the trolley is 0.7Kg 0r 700 grams so the formula will be : -
KE = 0.5 x 0.7 x mass of trolley x velocity²
Energy stored in a spring = ½ kx² when k =spring constant
x =compression
Table of Results
Here are my sets of results for both the simulation and light gate methods.
Computer Simulation
Light Gate
Average Speeds
Computer Simulation
Length of card = 0.1m
Light Gate
Length of card = 0.1m
Kinetic Energy for Computer Simulation
Kinetic energy (J) for Light Gate
From this scatter diagram showing the average velocity of the trolley, when using the computer simulation method, you can see that as the compression of the spring increases, so does the velocity of the trolley. You can see that the compression of the spring each time, relates to how much faster the trolley goes.
From this scatter diagram showing the average velocity of the trolley when using the light gate, you can see that the pattern is very similar to the one found using the computer simulation. It shows that as the compression of the spring increases, so does the velocity of the spring.
These two graphs prove that my prediction is correct. As the compression of the spring is increased, the velocity of the trolley also increases.
This scatter diagram shows the relationship between the compression of the spring, and the kinetic energy. This scatter graph shows that as the compression of the spring increases so does the kinetic energy.
It shows that as the compression of the spring is increased, so is the amount of kinetic energy.
The results for both the computer simulation and the light gate follow a pattern. And this pattern is, as the compression increases so does the kinetic energy.
Analysing Results
There is a clear pattern ermerging between the compression of the spring and the kinetic energy. Also the relationship between the amount of compression and the energy that is stored in a spring.
Even though both of the experiments had the same variables, for example the weight of the trolley and the length of the card, you can see that the results were not identical. The times for the computer simulation were faster than the times of the light gate.
This could be due to a number of reasons, but I feel that the main reason for this is that, whilst I was doing the light gate experiment, there will have been friction created by the trolley on the surface it was running on. This will have had an effect on the overall time of the trolley passing through the light gate. Whereas friction will not have been taking into account for the computer simulation.
Evaluation
There are factors in my experiment that will have caused errors. For example, I noticed that the wheels of the trolley used in the light gate experiment skidded. This meant that some of the energy stored in the spring was wasted as the wheels went round but the trolley did not move. This is one problem I encountered whilst doing the experiment, however it would be difficult to avoid if I did the experiment again.
There is also chance of the temperature effecting the spring and trolley in the light gate test. This is because the experiment took place over two lessons. However, as I explained in my analysing of results, friction will have been the main problem encountered.
If I were to do the experiment again I would try to take the friction into account, and maybe somehow take the amount of time wasted on this off of the final results for the light gate. This would give me a more even and fairer set of results.
Overall I feel that the experiment was a success as my prediction was proved correct and backed up by my results.
