I chose top do a preliminary test in order to familiarise myself with the experiment and the method of using the equipment involved. I also chose to do this because if I found a way of carrying out the experiment using a better technique to gather more reliable results, I also did a preliminary test in order to choose suitable heights for the experiment and to decide to what degree I will be measuring the diameter with e.g. 2 D.P.:
Evaluation of preliminary results:
In my preliminary test I measured the diameter of the crater to 1d.p. This is not reliable enough due to the fact that when I was measuring the crater I measured it to my assumption. In order not to let this affect my final test I will not measure it to 1.d.p. but rather to 1 significant figure. Also when
Equipment setup:
Tin of sand: This is what the marble will be dropped into so that it leaves a crater that we can measure.
Marble: I will use a marble to complete this experiment. The marble will be dropped from various heights to cause a crater.
Meter stick: I will be using a meter stick to measure the height of which the marble will be dropped from.
Pole: the pole will be used to help suspend the Clamp and Arm Clamp
Clamps and Arm Clamp: a Clamp and Arm Clamp will be used to hold the meter stick in place whilst the marble is being dropped into the tin of sand which will make the results more fair and reliable.
Compass: a compass will be used to measure the crater the marble has created which will then placed against the ruler to record the length.
Ruler: I will use a ruler to measure the distance of the crater caused (1d.p.).
Method:
In this experiment I will drop the marble at 12 different heights to achieve more reliable results also to achieve more accurate results I will drop the marble three times at each height and find the mean of all three droppings by using the formula: (Mean =sum of elements/number of elements).I also had to use the formula (²/₃∏R²) in order to work out the volume of the crater caused by the marble.
- Firstly attach the clamp to one end of the pole.
- Then the other end of the clamp to the arm clamp
- Secure the meter stick in the Arm Clamp with the length reading ascending.
- Line up the bottom of the meter stick with the tin of sand so the bottom of the meter stick reading 0cm is inline with the surface of the sand.
- Draw up a table to plot the results in including 3 diameter columns for each of the chosen heights and also a range and mean average column.
- Check that the level of the sand is level and at the right height have chosen.
- Drop (don’t throw) the marble from the desired height. when dropping marble make sure you look at the marble at a level angle and also when dropping the marble for example if you are dropping it from a height of 30 cm place the base of the marble at 30cm not the top of the marble or lining the marbles midway point at 30cm.
- Slowly and carefully remove the marble from the sand in order not to push the marble in more which will affect the results
- Take your compass and place each point onto two edges directly opposite each other which intersect the midpoint of the crater.
- Place the compass against the ruler to measure the width of the crater and record the results to 1d.p. when measuring look at the ruler directly on the side to get a more accurate reading.
- Repeat three times for each height. (After each be sure to level the sand so there are no craters or lumps on the sand before the marble has been dropped).
Safety:
When handling the compass be sure not to cut and/or poke anyone and yourself, do this by only holding the compass by the opposite end of the point. Overall in this experiment there is a minimal chance of being injured.
Results:
Graph analysis:
In both the volume and diameter graph I believe that both the heights of 15 cm and 35 cm are both anomalies in this investigation due to the fact that they both do not fit the line of best fit on both graphs. Although with the rest of the graph there is a strong positive correlation with my results which relates back to the prediction and theory of gravity (the higher I drop the marble the bigger the effect of gravity and kinetic energy therefore causing a bigger crater). One thing I can predict with my graph is that there is a limit to how big the crater can become this is clear from the graph because on both graphs there is a slight curve near to the end which I predict that will level off at some point due to the fact the it will not be able to gain anymore speed at some point onwards.
Evaluation:
Things I could do to improve:
I could improve this experiment by measuring the crater using callipers to measure the distance of the crater caused by the marble from one end to the other using callipers instead of using a ruler which is much less reliable because during the experiment we could have looked at the ruler from a different perspective which gives the illusion that the reading is smaller or bigger than what it actually is which would make our results void. Also when dropping the marble be sure to look at the marble at a level angle to ensure it is being dropped at a level height. This could be improved by having a platform which is attached to the ruler and can also be moved to any level of the ruler to roll the ball off since the effect of gravity will not have any difference being rolled. In order to improve my reliability of the results I
What I have done to minimise errors:
I have been extremely careful to minimise the amount of mistakes that I make in this experiment by simply holding the pole in a straight line as it often leans to the side therefore changing the height of which the marble is dropped from.
Conclusion:
In conclusion to this experiment I believe that I have proved the theory of gravity correct and that there is a definite correlation with the size of the crater and the height of which it is dropped from. Although I have encountered a few problems in this experiment I still believe that my data is reliable, but in order to achieve more reliable results I could carry out the experiment again but also improving it using what I mentioned.
