Fair Testing:
When the weight was held in the air, in preparation for its release no additional force was applied. It was just held and then released, ensuring the test remained fair. When releasing the weight I ensured that the weight was not tilting towards one direction, when held. Otherwise one part of the weight may have hit the ground before the other half and this may have affected the trace. When the weight hit the ground the power supply to the ticker timer was immediately disconnected. This was done so that no extra dots were added to the trace when the weight was resting, ensuring the most accurate reading that was possible. The ticker timer was not on a flat base because the workbenches were too low and did not give a good trace.
Conclusion:
Hypothesis: I believe that the trace produced will show that the space between the dots gradually increases. This will then allow me to find out the value of acceleration.
One factor that will affect acceleration is the potential energy. Potential energy is stored energy possessed by a system as a result of the relative positions of the components of that particular system. In this case it is a weight with a mass of 100 grams, which is attached to a length of ticker tape; this is held at a certain height, and then released. In this experiment gravitational potential energy, is changed to kinetic energy. The weight then accelerates downwards.
Acceleration is a which is defined as "the rate at which an object changes its ." An object is accelerating if it is changing its velocity. Objects in a gravitational field experience a downwards force, this is usually their weight. If this is unbalanced, this will result in acceleration downwards. In this case the forces are unbalanced the downward force is greater and it falls to the ground.
Evaluation:
There are many things that could have been improved in this experiment, an example of this is the ticker timer was not placed on a solid surface, instead it was held. This meant that the ticker tape, to which the weight was attached, was also held higher to emphasise the height, in the hope we could obtain a good trace. However, this meant that a slight slip or movement may have altered the height and affected the trace. This is what happened to me the first time I did the experiment. The result of this movement was that the dots instead of their distance between each other increasing, it decreased, resulting in something like this:
This was obviously wrong so I did the experiment again and ended up with a much more respectable trace which clearly depicted the distance between the dots as gradually increasing. I therefore decided to use this new trace.
As well as that, this experiment was not repeated so the chances of error are greater. The reason being, if this experiment had been repeated three times or so then an average of the initial and final distances could have been obtained. This would therefore have meant that any anomalous readings would have been highlighted and removed or they may have affected the average readings. This may have caused problems later on in the experiment, for example: inaccurate final calculations of the value of acceleration. Although I do believe that my trace was good and that the values I obtained were reasonable, but I did not get an answer close to 9.81ms-2.
Moreover, the reason I did not get 9.81ms-2 may have been because factors such as air resistance and may have had an affect on the experiment. This may have caused the value of acceleration to decrease. As well as that, the mass used, may not have been exactly 100 grams and this could have had an adverse affect on the experiment, reducing the actual value of acceleration. As well as that, the slight difference in the value of acceleration may have been caused because the exact values from the calculations may not have been used, as the calculator can not display them all. So these slight differences in the initial calculations may have affected the final value of acceleration.
Furthermore, when carrying out this experiment one vital safety aspect was missed out as the weight that was being released may have hurt someone if it landed on their foot. However, by placing empty cardboard box on the floor to catch the chain should ensure that no one's foot is at risk. The area occupied by the box may also have served as a clear area where your feet should stay away from. It also functions as a target, so it is clear to you and everyone else where your weight will be falling and they will stay away from there.
In addition to this, the measurements of the initial and final distances were not completely accurate as this was done by eye. Carrying on, we were not measuring in hundredths etc. It was limited to tenths. Since we were using a ruler. This also reduced the accuracy of the readings.
As well as that, the weight could have been released from a higher height so that we could have obtained longer traces. This may have given us a better trace for the initial and final distances, which would have allowed us to obtain a more accurate reading of the acceleration.
Finally, when comparing my answer to the actual value of acceleration the percentage error of the value I have obtained is almost 73%.
Alternative methods of carrying out the experiment are shown below:
The same method is used, as in the experiment above, however, in this experiment there is more control over the height and the weight it self, as you can just hold the paper tape. Also this reduces the kind of curved path that was taken by the weight when it was held up in conjunction with the ticker timer. This is because the ticker timer is not on a flat base and may not be directly behind and below the weight. Carrying on, it may be slightly to the left or right of the weight; this may therefore affect the path the weight takes downwards. This happens because the general movement of the ticker tape is not straight but instead it moves through the ticker timer metal housing slightly to the left or right causing the slight curve in its downward path. However, with the arrangement shown above this is not a problem as the path it takes is not affected in anyway, it is independent.
Another improvement could have been to use a light gate, as this would have allowed more accurate results:
1. Set up the equipment as shown. Measure the mass of the trolley car with string & interrupt card attached.
2. Launch and set-up the Timing Software.
3. A set mass of 100 grams will be used.
4. Hold the trolley car in the start position. Check that the string moves freely over the pulley with the weight attached and that the trolley car will move in a straight path through the light gate without colliding with anything.
5. Return the trolley car to the start position. Click on the Run icon to start the timing software and release the trolley car. The acceleration of the car will be measured as the interrupt card passes through the light gate and should appear in the Table & graph on the computer screen.
6. Click on the Run icon to turn off the timing and move the car back to the start position.
7. Click on the Run icon to re-start the timing & release the trolley.
This is an alternative method that can be used to calculate acceleration due gravitational potential energy.
