Experiment to Find the Acceleration Due to Gravity Using Free

Experiment to Find the Acceleration Due to Gravity Using Free Fall Essay As the title suggests, this experiment is to find the acceleration any object under free fall will undergo when travelling towards the earth. We presume in this experiment that we are unaware of the constant g and the basis of this experiment is to rediscover this value. Apparatus The principle behind the circuit is fairly simple. The ball is held through magnetism to the electromagnet; however when the magnetic field is no longer being created i.e. the switch is opened, the ball falls. When the switch is opened, the timer also starts as the switch is connected to one of its inputs. The ball strikes the metallic plate as it falls and breaks the contact between the metal plate and the rest of the circuit. The plate switch is also connected to the timer which then stops timing. In this way the time taken for the ball to fall a certain height is measured and hence its acceleration. The height fallen by the ball is measured by moving the plate switch up and down a wooden pole and measuring through use of a tape measure the distance between it and the bottom of the ball. All distances given in the data were from the top of the metallic plate to the bottom of the steel ball. The distance had to be standardised as the rate of acceleration depends upon the exact distance fallen in a certain amount of time. If we had not worked out two standard points that all our measurements were taken from we would not have been able to calculate the acceleration of the ball to an accurate degree. The acceleration acting upon the ball as it falls towards the earth is due to gravity. It is therefore prudent to show some understanding of the physics of the experiment before we actually look at the data itself. All following material is taken from Explaining Physics A-Level Edition by Stephen Pople. Gravity is a force of attraction between any two masses. This force is unusual as it is the only force discovered that has no repulsive effect unlike for example, magnetism which can attract and repel other masses. The Earth is surrounded by a gravitational field which exerts a force on any mass in it. In terms of this experiment the ball is attracted towards the earth as it falls. I read that experiments done in the past have shown that at a particular place all bodies falling freely under gravity in a vacuum or where air resistance is negligible have the same constant acceleration irrespective of their masses. This is why for this experiment the mass of the ball is irrelevant as long as it remains constant throughout the experiment. This is due to the fact that acceleration due to gravity is a constant for all objects irrespective of mass where air resistance is negligible. If we wish to find the acceleration due to gravity we only need to know the displacement of the ball and the time taken for it to fall that distance. This value is taken as 9.8m/s/s; that is to say that the velocity of any body travelling downwards will increase by 9.8m/s every second neglecting the effect of air resistance. As a result, my initial prediction is that the time taken for the ball to hit the plate will increase as the distance increases and as a result the acceleration will increase. This prediction is based upon the evidence found in the textbook mentioned above but also through initial examination of the data. For this experiment my partner and I decided to attach the metal plate switch at 20cm intervals from 20-200cm so a wider range of results could be calculated. We wished also to see if we could obtain the terminal velocity of an object in free fall i.e. the speed at which it will stop accelerating but the distance between the ball and the switch was not great enough. The final graph I will plot will be the displacement of the ball bearing over the time taken to open the switch squared. The two values should show positive correlation as if we arrange the equation from the textbook: S=ut + 1/2at s/t = u/t + 1/2 a Therefore: s/t = u/t + 1/2 a We know that intital velocity is Zero so: s/t = 1/2 a This rather conveniently allows us to find the acceleration due to gravity by simply doubling the gradient. g = 2( s/t) We see now how it is possible to obtain a value for g as I have data on both the displacement of the ball bearing and the time taken for it to fall that distance. An initial graph without reference to the data should be virtually straight line taking experimental error into account, perhaps looking roughly so: I have shown here the time squared for an object to fall over 50cm. I have taken g to be 10 which I have read is an approximate value. We see here that the time taken to fall increases proportionally to the displacement. I believe this will be true for the actual data also but need to plot this also. Displacement (cm) Time1(s) Time2(s) Time3(s) Average time(s) Average time Squared(s) 20 0.145 0.201 0.202 0.183 0.033 40 0.291 0.291 0.290 0.291 0.084 60 0.351 0.349 0.350 0.350 0.123 80 0.403 0.405 0.405 0.404 0.163 100 0.454 0.454 0.454 0.454 0.206 120 0.496 0.497 0.497 0.497 0.247 140 0.538 0.537 0.537 0.537 0.289 160 0.569 0.575 0.575 0.573 0.328 180 0.610 0.610 0.610 0.610 0.372 200 0.632 0.632 0.633 0.632 0.400 The highlighted result is the one I see as anomalous; I will explain later the major sources for error in the experiment. We see that the graph is almost a straight line showing that my initial prediction was correct in that the time squared had a positive correlation with the distance travelled. Let us presume now that we do not know that g is 9.8m/s/s and work it out based upon data on the graph. We know from my previous rearrangement of the equation in the textbook that the acceleration is the gradient doubled. To work out the gradient we must divide the change (delta) of they Y axis by the change of the X axis. When plotting the gradient it is wide to take it over the widest range possible to take all results into account. As a result I have decided to take the results from the extreme points of both the displacement and time. This is why I took the displacement over two metres instead of one to obtain a wider range of results. The data is taken from 20-200 cm. This is 180cm. However the modern convention is to measure length in metres which gives us a change of 1.8 m. The change along the X-axis is equal to 0.4-0.033 which comes to 0.367 If we divide 1.8 by 0.367 the result comes to 4.905 which we know is half the acceleration. If we double this value we find that (barring experimental error) the acceleration of the ball was 9.809 m/s/s which if we round up to 9.81m/s/s we find that it is very close to the conventional value for g. This does not leave us much room for experimental error as the variance between the value I obtained and the value stated in any textbook is 0.1m/s/s. However I believe there were sources of error for this experiment in general which I will now outline irrespective of the fact that they did not affect my own. The most significant factor when measuring g is that air resistance will act upon the ball. Explaining Physics tells us that we can neglect this factor as the ball itself is very dense. However, air must provide some resistance to the ball falling and could conceivably affect an experiment especially as air resistance isnt the same from one moment to the next for example, someone could open a window and cause an air current to act upon the ball. The only real remedy for this factor is to perform the experiment in a vacuum. A less likely factor to affect the experiment is the fact that the ball may display residual magnetic properties through repeatedly being attached to the electromagnet. The atoms within the ball could well have been ordered to make the ball itself be attracted to the electromagnet after the switch was thrown. Even if current was no longer flowing through the wires around the core, a weak magnetic field may have been apparent in the ball causing it to be attracted towards the iron core due to previous use. While iron is magnetically soft and would probably not have magnetic properties once the switch was opened the ball is made of steel which can retain magnetic properties. A solution for this problem would be to demagnetise the steel ball by either using a demagnetising tool or by simply heating it up by placing it in a naked flame for several seconds. One improvement I would have like to make to the experiment concerned the metal plate switch. I realised that it took a certain amount of time to actually break the contact between the plate itself and the rest of the circuit which could affect the overall time recorded by the Digital voltmeter. I believe it would be more efficient for a light sensor and a laser to replace the plate switch so the ball could fall uninterrupted and the time recorded would be more accurate. This is due to the fact that breaking a light beam can occur almost instantaneously while a metal plate is more difficult to move. If I had more time I would have liked to increase the distance over which the ball fell. This would not only provide a more accurate value for g but would also allow me to calculate the terminal velocity of a given mass. Ideally it would be interesting to see how the gravitational field of the earth varied in different locations, perhaps by obtaining data on the acceleration of the ball in various geographical locations. It would then be possible to see how g can vary due to the fact that the mass of the earth is not a constant all across the surface.

Canadian Law Enforcement Essay -- Technology, Tasers

â€Å"Taser Changes go Ahead†, an article published in the Alberta News in February, indicates that the RCMP is moving forward and will be instituting some previously described changes into its 2011 Police Manual framework. The framework is currently being reviewed and will later be reviewed and approved by the Albertan Solicitor General. The 16 recommendations made by the Braidwood inquiry, including yearly re-trainings, monthly quality and adherence audits, as well as updated procedures based on the minimization of any potentially adverse health effects to the subject, should be reflected in the final version of the manual for 2011. This establishment of the project by the Alberta Solicitor General demonstrates a significant attempt towards improvement over previous perspectives on the dangers of Conductive Energy Weapons, commonly known as Tasers. As a result, it is clear that improvements to the issues of adverse health effects, design flaws within the device itself and po lice policies must be instituted within the Canadian society. The issue of Conductive Energy Devices (CED), synonymously known as Conductive Energy Weapons (CEW), has been at the forefront since the introduction of the devices to the Canadian Market in 2001. The device most popularly known as a Taser has been allegedly responsible for numerous deaths caused by excessive use, flaws in the design, and lack of police training. Moreover, since the increased media coverage of the issue by non profit organizations such as Amnesty International, which began in late 2007, and the Canadian Civil Liberities Association in 2010 the use of such weapons has undergone significant change within the implementation of the device by police, codes of conduct governing CED equipp... ... number of Taser reported issues in the past decade. In conclusion, it is clear that albeit the Taser technology in its infant stage encountered many problems the fact that such a technology has not been taken off the market stands as a testament to its utility to law enforcement agencies worldwide. Furthermore, albeit the problem is complicated, time sensitive and requires significant mobilization of state resources and public participation as well as deaths of innocent civilians the issue is resolvable. As occurred in the past history of Taser failures the technology can and will be revamped whilst the society must catch up to fully optimize its utilization of the technology to achieve its goal. In the case of Tasers it is to provide a non lethal alternative to apprehend suspects, saving lives every step of the way, suspect and innocent alike.

Creation and Reality †By Michael Welker

Welker has written the book as a major review of creation as a theological theme. Two beliefs drive Welker's understanding of the issue. He is thoughtful to the up-and-coming crossing point with science in his re-examination of what creation is, with reference to new knowledge and with a concern for environmental issues. Secondly, he is aware that theological thinking has become a series of cliches that now needs to be held up to careful study.However most importantly, Welker finds new ways of thinking about creation. Welker structures the writing in a way which enables it to be forthcoming to the reader. Due to the fact that theology can be such a difficult issue for some, being written in a coherent and precise way is exactly what was needed of his writing. Welker’s concerns with the issue are made fairly evident. Through his writing he shows a love for the subjects he discusses, which is highlighted through his deep and thoughtful thinking.With this careful attention to det ail, it backs up the fact that Welker found it very important that he paid attention to detail all the way through the book. In the article, Welker believes the ways in which â€Å"bourgeois theism† has understood creation as a one-sided act of an uplifting God in a single act of lonely sovereignty. Welker suggests that in Genesis 1-2, the â€Å"normative† texts on the subject, such transcendence is not what is offered.Rather, creation is â€Å"the construction of associations of interdependent relations,† a formation and protection of interactions among creatures. From this, two other fresh theses emerge. First, the individual is engaged â€Å"in the activity of separating, ruling, producing, developing and reproducing itself,† that is, in the very actions and functions usually assigned to God. The person is an active agent in the processes of creation.Second, God who presides over the process of creation not only acts, but also reacts to the initiatives taken by the individual. These sorts of statements of course sound strange in the midst; but it is exactly Welker's point that such classical thought has operated with assumptions and categories that are at some remove from the affirmations of the text. From this principle, Welker considers in turn a series of issues including natural revelation, angels, image of God and human dominion, and sin and fall.Welker's small book, is reflective of his larger research program, a claim that theological work now is called and pushed beyond conventional categories with which the church has grown comfortable. The move beyond will much more likely permit theology to make thoughtful contributions that will be taken seriously in other disciplines that now may be the engaged dialogue partners of theology. This is likely to be his main reason for writing the book – his passion for the issues that it involves. References Welker, Michael. Creation and Reality. Fortress Press: Minneapolis, 1999 .

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