24 9. A research engineer is testing the effectiveness of the braking system of a car when it is driven in wet conditions. The engineer measures and records the braking distance, d metres, when the brakes are applied from a speed of V ௘NP Kí . Graphs of d against V and log10 d against log10 V were plotted. The results are shown below together with a data point from each graph. d (30, 20) O V O log10 d í log10 V Figure 5 Figure 6 (a) Explain how Figure 6 would lead the engineer to believe that the braking distance should be modelled by the formula d = kV n where k and n are constants with k | 0.017 (3) Using the information given in Figure 5, with k = 0.017 (b) find a complete equation for the model giving the value of n to 3 significant figures. (3) Sean is driving this car at 60 km hí in wet conditions when he notices a large puddle in the road 100 m ahead. It takes him 0.8 seconds to react before applying the brakes. (c) Use your formula to find out if Sean will be able to stop before reaching the puddle. (3) _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________