2012年11月IB物理(SL)真题PDF下载-paper2
A1. Data analysis question.
The movement of glaciers can be modelled by applying a load to a sample of ice.
After the load has been applied, it is observed to move downwards at a constant speed v as the ice deforms. The constant speed v is measured for different loads. The graph shows the variation of v with load W for a number of identical samples of ice.The data points are plotted below.
The uncertainty in v is ±20 μms–1 and the uncertainty in W is negligible.
(a) (i) On the graph opposite, draw error bars on the first and last points to show the uncertainty in v.
(ii) On the graph opposite, draw the line of best-fit for the data points.
(b) Explain whether the data support the hypothesis that v is directly proportional to W.
(c) Theory suggests that the relation between v and W is
v=kW3
where k is a constant.
To test this hypothesis a graph of v1/3 against W is plotted.
At W =5.5 N the speed is 250 ±20 μms–1.
Calculate the uncertainty in v1/3 for a load of 5.5 N.
(d) (i) Using the graph in (c), determine k without its uncertainty.
(ii) State an appropriate unit for your answer to (d)(i).
A2. This question is about magnetic fields.
A long straight vertical conductor carries an electric current. The conductor passes through a hole in a horizontal piece of paper.
(a) State how a magnetic field arises.
(b) On the diagram below, sketch the magnetic field pattern around the long straight current-carrying conductor. The direction of the current is into the plane of the paper.
(c) The long straight conductor is formed into a coil consisting of two separate turns, X and Y. The coil hangs with its axis vertical.
Assume that the turns of the coil each behave as a long straight conductor.
(i) Explain why, when there is a current in the coil, the separation of X and Y decreases.
(ii) The current in the coil is 15 A and the circumference of one turn is 0.48 m.In order to restore X and Y to their original separation, a mass of 2.8 ×10–4 kg is suspended from turn Y. Estimate the magnetic field strength at X due to Y.
A3. This question is about radioactivity.
Caesium-137(13755Cs) is a radioactive waste product with a half-life of 30 years that is formed during the fission of uranium. Caesium-137 decays by the emission of a beta-minus (β– ) particle to form a nuclide of barium (Ba).
(a) State the nuclear equation for this reaction.
(b) Determine the fraction of caesium-137 that will have decayed after 120 years.
(c) Explain, with reference to the biological effects of ionizing radiation, why it is important that humans should be shielded from the radiation emitted by caesium-137.
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