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kw0573 last won the day on January 21

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About kw0573

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    May 2015
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  1. When the air in the refrigerator is cooled, the force applied by the room air is greater than the force from the air within the refrigerator. Did you try to take the difference and do P = F/A?
  2. That should be your decision, but assuming your grade increases with each attempt, you should do reasonably good job on earlier tries to prepare for the last. You dont want to goof on first two only to have learned nothing useful for the final attempt.
  3. Definitely AA SL. AI HL is much harder than AA SL and is for the most part unnecessary for med.
  4. It would be a good idea to switch to Physics SL and Economics HL. But the difference in difficulty is not very big between SL and HL in Physics, so don't expect everything to be easy all of a sudden.
  5. It's a reasonable to mark you down for this. Your statement is a bit ambiguous. Interpretation 1: getting extraneous data / not sure why data was collected: If you don't know what you are doing then that indicates lack of understanding of the experiment. Interpretation 2: if your conclusions contradict literature for a well-known experiment/theory then clearly you did something wrong and you were not able to explain what it is. If you confuse the graders they will mark you down it's very simple.
  6. @sdcibwqa I think AA SL is best for you. @NisplayDame I am not familiar with AP Stats, but it should have more statistics than IB AA HL.
  7. @duarte If you are superb at Maths, you should look to take one of the new HL courses; if you are average, take AA SL, if you are very bad at Maths, take AI SL. In light of changes to the Maths curriculum, this thread is locked from additional replies.
  8. @benjeren 1. There was a typo in the original question as you can't concentrate a solution by adding more water. Likely it was 5.0 cm3 of initial solution, at which the new concentration is just 100 fold more dilute or 0.010 mol dm-3 2. I concur with your answer, but clearly you meant n = PV/RT. 3. a) The phosphorus occurs in P4 in its elemental form, as provided in the question. So the molar mass is 4 × 30.974 = 123.90 g/mol 2.478 g / (123.90 g/mol) = 0.0200 mol of P4. b) P4 is still limiting, but 0.5/3 is 0.167 c) 0.500 mol of hydroxide - 3mol of OH/mol of P4 * (0.020 mol of P4) = 0.440 mol of hydroxide in excess d) phosphine is PH3, which is in 1-to-1 mol ratio as P4. Also 22.7 is in dm3, so you need to use 22 700 cm3 0.02 mol (22 700 cm3/mol) = 454 cm3.
  9. Finding correlation in physics or chemistry IAs is just not what the examiners are looking for. Yes there is a non-zero correlation but you are not able to find it and the findings won't explain anything. IAs should be about theories whether they describe experimental findings. If you are so set on bond angles, you can look at how different functional groups affect bond angles or bond lengths. However, database IAs tend to score statistically poorer than IAs with a reaction or some laboratory work.
  10. @ChocolateAndVanilla I would say stay in AA SL. There are many online resources available (especially from non-IB sites) that can help. AA SL should in theory leave more doors open.
  11. It's a good start but you have to flesh out the details further to narrow the scope of your investigation. As a next start you should find the shape of spinning tops in terms of a particular equation that you can optimize.
  12. I would suggest that you find a book on cancer cell growth (including biomolecular engineering textbooks). Certainly they have problems on cancer cell growth and you can just take the numbers in the question. I wouldn't focus on "modelling from data" as much as "modelling from assumptions". It's very easy to play around with assumptions to suit your needs but as a high school student it's difficult to find or make up good data.
  13. I don't have the specific subject reports so my interpretations may be skewed. "Analyze the limits" means to identify limitations or potential next steps for the IA, in terms of the investigation, scope, or assumptions. For what circumstances does your IA is valid? Can the conclusions be extended to other scenarios? What is something you would like to improve about the IA? "Looking at it from different perspectives" likely means multiple approaches from solving the problem. For your mixing problem, you may be able to set up the same initial differential equation multiple ways, solve the DiffEQ multiple ways, or to set up entirely different DiffEQ for the same scenario. Looking at subject reports is definitely a correct and important step to take. Keep it up!
  14. The relevant quantities in this question are the 1) time 2) initial velocity 3) displacement 4) acceleration. The corresponding equation is s = ut + 1/2 * at^2 Let down be the positive direction. s = 4.81m, u = 12.7 m/s, a = 9.81 m/s^2, t = ? Plug the values into the quadratic and solve for the positive t. t = 0.335 s
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