[ 493 ] Physical Science GED ® TEST SCIENCE FLASH REVIEW • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Refer to the following passage to answer the next three questions. When applying the brakes in a moving car, the force of friction between the road surface and the vehicle tires is what stops the car. The force of friction depends on the coefficient of friction, which varies with the road conditions (dry, wet, icy) and seasons (summer, winter). In an accident, a police officer can measure the braking distance by the skid marks, note the road conditions, and determine the initial velocity of the car. The data are shown in the graph. 0 10 20 30 40 80 70 60 50 40 30 20 10 0 Initial v (m/s) 0.6 (dry summer) 0.2 (icy winter) 0.4 (wet spring) Braking Distance (m) On a road under wet spring conditions, a car has a braking distance of 40 m. The initial speed of the car was ______ m/s.