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Hooke's Law

As it stands, this is a simple treatment of a simple experiment and would only get low marks. It is not that what you have written is wrong, it is just that nothing is fully explained. You mention that Hookes Law can predict how a elastic material will behave when weights are added to it, but you never actually say what Hooke's Law IS, nor do you actually use it in the experiment. Very little science is used and your prediction - "I Predicted That The Elastic Bands Would Snap" is actually nonsense, as you weren't USING elastic bands! You would be expected to predict how the weight added would effect the amount of stretch. I'm not even sure if Hooke's law really applies to plastic bags, as they are not really elastic - they never spring back to their original shape. You mention about making the test 'fair' but don't say how. Questions about your conclusion: "My prediction was correct. The difference in width did affect the elastic point on the weights bag strips.HOW? IN ANY CASE, YOU DID NOT PREDICT A SPECIFIC EFFECT OF WIDTH. Due to having foreknowledge of Hooke's Law it was easy to roughly predict what the results were going to be.BUT YOU DIDN'T! HOW WOULD YOU USE HOOKES LAW??? Also being aware of the movement in molecules that are found in solids was helpful. HOW? WHAT 'MOVEMENT OF MOLECULES'?This helped me come to the conclusion that due to the amount of pressure on certain parts of the strip a wider strip would be able to withstand more pulling from the weights". For your evaluation: "The experiment managed to produce some decent, accurate results so that I was able to produce a graph and come to a good conclusion. All of my results seemed to be very accurate. EVIDENCE? They all followed a pattern until they reached the elastic point. After they had hit the elastic point the results became harder to record because they were so varied. WHAT EXACTLY DO YOU MEAN? VARIED RESULTS TEND TO INDICATE THAT THE MEASUREMENT TECHNIQUE MAY NOT HAVE BEEN ACCURATE, AND MAY NOT HAVE BEEN RELIABLE.Also some of the measurements could have been slightly inaccurate because I was using a 30cm ruler.SO....??? To make sure that all my results were accurate I would have to have more time and be able to repeat them again.REPEATING INACCURATE RESULTS DOES NOT MAKE THEM ACCURATE - YOU NEED TO ADJUST YOUR METHOD TO TRY TO COMBAT INACCURACY. "

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Resistance in a Wire Investigation

Generally Ok but some points need sorting. You mention preliminary work but do not describe exactly what you did, you give no results, and you don't really make clear exactly what the purpose of the work was or how you altered your plan as a result. Your description of current and resistance mentions electron colliding with the wire. The electrons are part of the wire, so it is better to say that they colllide with the molecules that make up the material of the wire. You compare your results to the theoretical ones but you don't then go on to say if the differences noted weaken your conclusion significantlt (with reasons). Your first paragraph in evaluation seems to ignoire these differences completely. Extension work needs to be described in much more detail - if you use copper wire, for instance - what lengths? what voltage? etc.

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How Does Resistance Change With Length Of Wire.doc

"For instance the length of wire, this is a variable as the length of wire increases the time taken for the electricity to pass through it resulting in a higher resistance, e.g. like water flowing through a pipe as the water flows it encounters friction against the pipe the same can be said about the wire except the wires "friction" is the result of electronics colliding with the vibrating atoms of the wire".This is accurate, but I think you need a bit more detail to convince the examiner that you really understand, e.g. explain what a current is, and explain in more detail why electrons (not ELECTRONICS!) colliding with atoms in the wire results in resistance.More like you have done in your conclusion, in fact."To make sure that this is a fair and even test they are some things that most remain constant through out the experiment, for instance I must make sure that the gaps between each section off wire that I test are equal e.g. go up in tens or twenty's not random numbers like 1, 15, 22. This will insure a fair test".Making sure that the readings within the range are evenly spaced does NOT in any way ensure that the test is fair. It is good practice, because it makes sure that values within the range are evenly sampled, with no gaps, but if the method is 'unfair', a suitable range will not make it 'fair'! "I predict that in this experiment that resistance will be proportional to length". O.K., but why? You should justify this statement using science. "Here is my revised table of results as the early one hand a number if errors present on it" What were the 'errors' and how did you 'revise' your results? "for instance if we look at the resistance of a piece of wire 80 cm long which has a resistance of 4.2 and then of a piece 160 cm long which has a resistance of 9 we can see that there is all most a doubling effect going on, which will become apparent when I graph this data". As you imply in the last part of the sentence, picking two readings that fit your theory is not really convincing evidence, compared with measuring the slope of the graph to see if there is consisisten doubling. Neither of the lines of best fit on your graphs, and especially the second one, look as though they really are BEST fit. The line should pass through the origin as length 0 would give resistance 0.The second line is inaccurate - only one point lies above the line and EIGHT are below it!!!Because computer drawn graphs do not have a grid on them, accurate calculations of the slope of the graph are difficult - i suggest that you draw the graphs by hand on graph paper and put in the true line of best fit yourself! "I would include putting a larger amount of current through it and use a thicker or different type of wire both these would gave me more throughout and accurate data".WHY would this give you more accurate data? Explain! You should also give more detail - what thicknesses? What types of wire? What current? If you altered one of these, what lengths would you use - the same as before?
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