Section A

Answer all the questions in the spaces provided.

A1. This question is about electrical resistance.

The graph shows the variation with temperature T of the resistance R of an electrical component.

(a) A student hypothesizes that the resistance is inversely proportional to the temperature.Use data from the graph to show whether the hypothesis is supported.

(Question A1 continued)

(b) A second student suggests that the relationship is of the form

lgR = a + b/T

where a and b are constants.

The student plots the graph below. Error bars have been included for the sake of clarity.

(Question A1 continued)

(i) Explain how the graph drawn could be used as evidence to support the student’s suggestion.

(ii) Use the graph to determine the constants a and b.



(iii) Using your answers to (b)(ii), determine a value for the resistance of the component at a temperature of 260 K.


A2. This question is about forces.

An athlete trains by dragging a heavy load across a rough horizontal surface.

The athlete exerts a force of magnitude F on the load at an angle of 25° to the horizontal.

(a) Once the load is moving at a steady speed, the average horizontal frictional force acting on the load is 470 N.Calculate the average value of F that will enable the load to move at constant speed.

(b) The load is moved a horizontal distance of 2.5 km in 1.2 hours.Calculate

  • (i) the work done on the load by the force F.
  • (ii) the minimum average power required to move the load.

(c) The athlete pulls the load uphill at the same speed as in part (a).Explain, in terms of energy changes, why the minimum average power required is greater than in (b)(ii).


A3. This question is about solar heating panels.

(a) State the energy change that takes place in a solar panel.

(b) A village consists of 120 houses. It is proposed that solar panels be used to provide hot water to the houses.

The following data are available.

average power needed per house to heat water = 3.0 kW

average surface solar intensity = 650Wm−2

efficiency of energy conversion of a solar panel =18%

Calculate the minimum surface area of the solar panels required to provide the total power for water heating.




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