Acceleration is the rate at which the velocity of an object changes, over a period of time. It is measured in metres-per-second per second (m/s/s) or meters-per-second squared (m/s²), and it tells you how much the velocity will change each second. The acceleration of an object can be calculated by using the following formula:
(Average) acceleration (m/s²) = change in velocity (m/s) or in symbols: a = v – u
Time taken for the change (s) t
Where u is the velocity at the beginning of the time interval and v is the velocity at the end of the time interval. When an object is slowing down the change in the velocity is negative, and so the acceleration is negative. This is sometime called deceleration. The acceleration at any point on a journey can be calculated by measuring the slope of a velocity-time graph. In this is the same as applying the formula that I have included above. To show some of these graphs I have included some below to show how different accelerations can be portrayed for varying and constant changes.
Velocity (m/s) Velocity (m/s)
Time (s) Time (s)
Preliminary Experiment and Method:
Before any experiment is started, there should always be a trial run, to determine certain factors, in my experiment…which ball I am going to use, tennis ball, table tennis ball or a rubber ball… The formula of F = ma will be applied to one of the balls at a time, as I have chosen that ball, which will have its mass recorded before the experiment, and have its acceleration measured throughout. The speed at which it falls wilL be determined on how high the ball bounces back up.
I will have a 1m ruler, standing up vertical, I will drop the ball first from the height 10cm…and so on, each time the ball drops, I will take into consideration how high it bounces back up. I will do this to the 3 different balls.
I was pleased with what I managed to take out from my preliminary experiment. The ranges used for the results above are those that I will use for the final experiment. This is for a number of reasons.
Fair Test:
A fair test must be ensured at all times, in any experiment, to keep the results as accurate as possible so that appropriate conclusions can be drawn. The main way that I hope to achieve this is by repeating each of my results a further two times so that an average can be taken and any anomalous results can be spotted before they are taken as genuine ones. As well as this I must consider how accurate I want my results to be. As seen above, I have rounded each digit to the nearest cm. Another point is the set-up must be the same for both experiments, if this does not happen then I would not expect very accurate results at all. To make sure that my results are accurate I will only change one factor at a time. In fact there is only one factor that will be changed during the whole experiment.
Safety Precautions:
On the surface this is not a highly dangerous experiment, however what must be shown is awareness of the environment that it is taking place in. There will be many groups working within a very small area and these means that, if a ball was to go astray, some one could trip or fall. Therefore everyone will have to be vigilant as to where they are walking. As I am using a clamp to secure the meter ruler it will be kept securely on the bench so it is not knocked off the clamp being securely fixed.
Hypothesis:
Through my preliminary workings, and my initial scientific research, I have begun to understand what I think my final results will show. (See graphs)
Accuracy of Results and how they relate to my original hypothesis:
On the surface the accuracy of my results was quite poor, on the other hand I have accounted for the discrepancies that occurred. The only reason that my results are not very accurate is that I did not account for the friction in the system and if I had I'm sure that my results would have supported the hypothesis that I put forward, and in a light they actually do. The surface the ball hit could have changed, or I could have had more high tech equipment to measure how high it bounced, but I did not, and considering what I did have, I think I have made good use of it.
Evaluation:
Overall I was quite pleased with what I have managed to take from the experiment, not so much the results but the information, which I have been able to take out of it. Although my results were the readings that I expected to take, I was very happy indeed with the procedure and the way in which I still managed to maintain fair conditions for it to take place. Of course if I did indeed do the experiment again I would have to take different aspects into consideration.
The main aim of my experiment was to prove that the higher you drop a ball from, the higher it will bounce overall. The bottom line is that I think I proved this point very well.
Further Experiments:
The next experiment that I would put into action would be either of the ideas that I have suggested in the last section so that my overall results would be closer to those that I had expected.
