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1. SL and HL This was often well answered. Some candidates did not define momentum but instead attempted to give a qualitative description. A significant number of candidates talked about “lost” rather than “transformed” energy. 2. SL only The definition of gravitational field strength was often incorrect. 3. [SL only] Circular motion It was satisfying to see many correct answers to all parts of this question. The vectors in (a) were correctly drawn and the calculation in (c) was complete. A few students lost a mark for significant digits in (c). 4. SL and HL It was common to find that candidates thought that the balance reading would be constant when the water is boiling steadily. However, many did refer to either constant temperature or a steady rate of production of bubbles. Very few candidates appreciated the reason for taking two intervals instead of one. Many referred vaguely to it being “more accurate” without saying why. It was pleasing to note that, when determining the gradient, very few used two points on the line that were close together. Very few candidates were able to determine the specific latent heat. Most answers did not include any factor to allow for the time of collection of the water. There were some good responses but many referred to ‘errors in the meters’ or ‘energy losses in the variable resistor’. 5. SL and HL (a) A significant number of candidates were unable to draw an appropriate straight line of best fit for the points provided, though this did not cause any difficulty to the majority. The most common mistakes were to attempt to draw the line without the aid of a ruler or to join the 1st, 3rd and 5th points. (b) Surprisingly, many candidates failed to use the intercept and/or the gradient of the graph in order to calculate required constants but instead they took data from two of the given points and attempted to solve a pair of simultaneous equations. Whatever technique used, many candidates made mistakes with the powers of ten and with units. (c) Very few candidates correctly suggested that the constant B should be zero; the most common error was to suggest the value 8.3 having confused this with the universal molar gas constant. 1 (d) Many candidates managed to pick up marks by showing that they were correctly working with the numbers that they had identified in parts (b) and (c). It was, however, common to see candidates make errors involving powers of ten. HL only (e) Only a handful of candidates attempted to approach this problem in an appropriate way. It was disappointing to note that only a small minority were able to calculate the total percentage error in any given reading of PV. These candidates were then often unable to progress any further with the determination of absolute error in the calculated value of the intercept. 2